American and British English spelling differences

Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography, the two most notable variations being British and American spelling. Many of the differences between American and British English date back to a time before spelling standards were developed. For instance, some spellings seen as "American" today were once commonly used in Britain, and some spellings seen as "British" were once commonly used in the United States.
A "British standard" began to emerge following the 1755 publication of Samuel Johnson's "A Dictionary of the English Language", and an "American standard" started following the work of Noah Webster and, in particular, his "An American Dictionary of the English Language", first published in 1828. Webster's efforts at spelling reform were somewhat effective in his native country, resulting in certain well-known patterns of spelling differences between the American and British varieties of English. However, English-language spelling reform has rarely been adopted otherwise. As a result, modern English orthography varies only minimally between countries and is far from phonemic in any country.
Historical origins.
In the early 18th century, English spelling was inconsistent. These differences became noticeable after the publishing of influential dictionaries. Today's British English spellings mostly follow Johnson's "A Dictionary of the English Language" (1755), while many American English spellings follow Webster's "An American Dictionary of the English Language" ("ADEL", "Webster's Dictionary", 1828).
Webster was a proponent of English spelling reform for reasons both philological and nationalistic. In "A Companion to the American Revolution" (2008), John Algeo notes: "it is often assumed that characteristically American spellings were invented by Noah Webster. He was very influential in popularizing certain spellings in America, but he did not originate them. Rather […] he chose already existing options such as "center, color" and "check" for the simplicity, analogy or etymology". William Shakespeare's first folios, for example, used spellings such as "center" and "color" as much as "centre" and "colour". Webster did attempt to introduce some reformed spellings, as did the Simplified Spelling Board in the early 20th century, but most were not adopted. In Britain, the influence of those who preferred the Norman (or Anglo-French) spellings of words proved to be decisive. Later spelling adjustments in the United Kingdom had little effect on today's American spellings and vice versa.
For the most part, the spelling systems of most Commonwealth countries and Ireland closely resemble the British system. In Canada, the spelling system can be said to follow both British and American forms, and Canadians are somewhat more tolerant of foreign spellings when compared with other English-speaking nationalities. Australian spelling mostly follows British spelling norms but has strayed slightly, with very few American spellings incorporated as standard. New Zealand spelling is almost identical to British spelling, except in the word "fiord" (instead of "fjord"). There is an increasing use of macrons in words that originated in Māori and an unambiguous preference for "-ise" endings (see below).
Latin-derived spellings (often through Romance).
"-our", "-or".
Most words ending in an unstressed "-our" in British English (e.g., ) end in "-or" in American English (). Wherever the vowel is unreduced in pronunciation, e.g., "contour", "velour", "paramour" and "troubadour" the spelling is uniform everywhere.
Most words of this kind came from Latin, where the ending was spelled "-or". They were first adopted into English from early Old French, and the ending was spelled "-our", "-or" or "-ur". After the Norman conquest of England, the ending became "-our" to match the later Old French spelling. The "-our" ending was used not only in new English borrowings, but was also applied to the earlier borrowings that had used "-or". However, "-or" was still sometimes found. The first three folios of Shakespeare's plays used both spellings before they were standardised to "-our" in the Fourth Folio of 1685. After the Renaissance, new borrowings from Latin were taken up with their original "-or" ending, and many words once ending in "-our" (for example, "chancellour" and "governour") reverted to "-or". Many words of the "-our/or" group do not have a Latin counterpart that ends in "-or"; for example, "armo(u)r", "behavio(u)r", "harbo(u)r", "neighbo(u)r"; also "arbo(u)r", meaning "shelter", though senses "tree" and "tool" are always "arbor", a false cognate of the other word. Some 16th- and early 17th-century British scholars indeed insisted that "-or" be used for words from Latin (e.g., "") and "-our" for French loans; but in many cases the etymology was not clear, and therefore some scholars advocated "-or" only and others "-our" only.
Webster's 1828 dictionary had only "-or" and is given much of the credit for the adoption of this form in the United States. By contrast, Johnson's 1755 (pre-U.S. independence and establishment) dictionary used "-our" for all words still so spelled in Britain (like "colour"), but also for words where the "u" has since been dropped: "ambassadour", "emperour", "governour", "perturbatour", "inferiour", "superiour"; "errour", "horrour", "mirrour", "tenour", "terrour", "tremour". Johnson, unlike Webster, was not an advocate of spelling reform, but chose the spelling best derived, as he saw it, from among the variations in his sources. He preferred French over Latin spellings because, as he put it, "the French generally supplied us". English speakers who moved to America took these preferences with them. In the early 20th century, H. L. Mencken notes that "' appears in the 1776 Declaration of Independence, but it seems to have been put there rather by accident than by design". In Jefferson's original draft it is spelled "honour". In Britain, examples of rarely appear in Old Bailey court records from the 17th and 18th centuries, whereas there are thousands of examples of their "-our" counterparts. One notable exception is '. ' and ' were equally frequent in Britain until the 17th century; "honor" only exists in the UK now as the spelling of "Honor Oak", a district of London and the occasional given name Honor.
Derivatives and inflected forms.
In derivatives and inflected forms of the "-our/or" words, British usage depends on the nature of the suffix used. The "u" is kept before English suffixes that are freely attachable to English words (for example in ) and suffixes of Greek or Latin origin that have been adopted into English (for example in ). However, before Latin suffixes that are not freely attachable to English words, the "u":
In American usage, derivatives and inflected forms are built by simply adding the suffix in all cases (for example, ', ' etc.) since the "u" is absent to begin with.
Exceptions.
American usage, in most cases, keeps the "u" in the word "glamour", which comes from Scots, not Latin or French. ' is sometimes used in imitation of the spelling reform of other "-our" words to "-or". Nevertheless, the adjective "glamorous" often drops the first "u". ' is a somewhat common variant of ' in the US. The British spelling is very common for ' (and "") in the formal language of wedding invitations in the US. The name of the has a "u" in it because the spacecraft was named after British Captain James Cook's ship, . The (former) special car on Amtrak's "Coast Starlight" train is known as the Pacific Parlour car, not "Pacific Parlor". Proper names such as "Pearl Harbor" or "Sydney Harbour" are usually spelled according to their native-variety spelling vocabulary.
The name of the herb "savory" is spelled thus everywhere, although the related adjective "savo(u)ry", like "savo(u)r", has a "u" in the UK. "Honor" (the name) and "arbor" (the tool) have "-or" in Britain, as mentioned above, as does the word "pallor". As a general noun, "rigour" has a "u" in the UK; the medical term "rigor" (sometimes ) does not, such as in "rigor mortis", which is Latin. Derivations of "rigour"/"rigor" such as "rigorous", however, are typically spelled without a "u", even in the UK. Words with the ending "-irior", "-erior" or similar are spelled thus everywhere.
The word "armour" was once somewhat common in American usage but has disappeared except in some brand names such as Under Armour.
The cardinal numbers "four" and "fourteen", when written as words, are always spelled with a "u", as are the ordinal numbers "fourth" and "fourteenth". "Forty" and "fortieth", however, are always spelled without a "u".
Commonwealth usage.
Commonwealth countries normally follow British usage. Canadian English most commonly uses the "-our" ending and "-our-" in derivatives and inflected forms. However, owing to the close historic, economic, and cultural relationship with the United States, "-or" endings are also sometimes used. Throughout the late 19th and early to mid-20th century, most Canadian newspapers chose to use the American usage of "-or" endings, originally to save time and money in the era of manual movable type. However, in the 1990s, the majority of Canadian newspapers officially updated their spelling policies to the British usage of "-our". This coincided with a renewed interest in Canadian English, and the release of the updated Gage Canadian Dictionary in 1997 and the first Canadian Oxford Dictionary in 1998. Historically, most libraries and educational institutions in Canada have supported the use of the Oxford English Dictionary rather than the American Webster's Dictionary. Today, the use of a distinctive set of Canadian English spellings is viewed by many Canadians as one of the unique aspects of Canadian culture (especially when compared to the United States).
In Australia, "-or" endings enjoyed some use throughout the 19th century and in the early 20th century. Like Canada, though, most major Australian newspapers have switched from ""-or" endings to "-our" endings. The "-our"" spelling is taught in schools nationwide as part of the Australian curriculum. The most notable countrywide use of the "-or" ending is for the , which was originally called "the Australian Labour Party" (name adopted in 1908), but was frequently referred to as both "Labour" and "Labor". The "Labor" was adopted from 1912 onward due to the influence of the and King O'Malley. Aside from that, "-our" is now almost universal in Australia. New Zealand English, while sharing some words and syntax with Australian English, follows British usage.
"-re", "-er".
In British English, some words from French, Latin or Greek end with a consonant followed by an unstressed "-re" (pronounced ). In modern American English, most of these words have the ending "-er". The difference is most common for words ending "-bre" or "-tre": British spellings all have "-er" in American spelling.
In Britain, both "-re" and "-er" spellings were common before Johnson's 1755 dictionary was published. Following this, "-re" became the most common usage in Britain. In the United States, following the publication of Webster's dictionary in the early 19th century, American English became more standardized, exclusively using the "-er" spelling. 
In addition, spelling of some words have been changed from "-re" to "-er" in both varieties. These include "chapter", "December", "disaster", "enter", "filter", "letter", "member", "minister", "monster", "November", "number", "October", "offer", "oyster", "powder", "proper", "September", "sober" and "tender". Words using the "-meter" suffix (from Ancient Greek -μέτρον "métron", via French "-mètre") normally had the "-re" spelling from earliest use in English but were superseded by "-er". Examples include "thermometer" and "barometer".
The "e" preceding the "r" is kept in American-inflected forms of nouns and verbs, for example, , which are respectively in British English. According to the "OED", "" is a "word ... of 3 syllables (in careful pronunciation)" (i.e., ), yet there is no vowel in the spelling corresponding to the second syllable (). The OED third edition (revised entry of June 2016) allows either two or three syllables. On the Oxford Dictionaries Online website, the three-syllable version is listed only as the American pronunciation of "centering". The "e" is dropped for other derivations, for example, "central", "fibrous", "spectral". But, the existence of related words without "e" before the "r" is not proof for the existence of an "-re" British spelling: for example, "entry" and "entrance" come from "enter", which has not been spelled "entre" for centuries.
The difference relates only to root words; "-er" rather than "-re" is universal as a suffix for agentive ("reader", "winner", "user") and comparative ("louder", "nicer") forms. One outcome is the British distinction of "meter" for a measuring instrument from " for the unit of length. But, while " is often spelled as "-re", pentameter, hexameter, etc. are always "-er".
Exceptions.
Many other words have "-er" in British English. These include Germanic words, such as "anger", "mother", "timber" and "water", and such Romance-derived words as "danger", "quarter" and "river".
The ending "-cre", as in "acre",<ref name="acre/louvre">Although "acre" was spelled "æcer" in Old English and "aker" in Middle English, the "acre" spelling of Middle French was introduced in the 15th century. Similarly, "loover" was respelled in the 17th century by influence of the unrelated Louvre. (See "OED", s.v. "acre" and "louvre")</ref> "lucre", "massacre", and "mediocre", is used in both British and American English to show that the "c" is pronounced rather than . The spellings "ogre" and "euchre" are also the same in both British and American English.
"Fire" and its associated adjective "fiery" are the same in both British and American English, although the noun was spelled "fier" in Old and Middle English.
 ' is the prevailing American spelling used to refer to both the dramatic arts and buildings where stage performances and screenings of films take place (i.e., ""); for example, a national newspaper such as "The New York Times" would use ' in its entertainment section. However, the spelling "theatre" appears in the names of many New York City theatres on Broadway (cf. Broadway theatre) and elsewhere in the United States. In 2003, the American National Theatre was referred to by "The New York Times" as the "American National ", but the organization uses "re" in the spelling of its name. The John F. Kennedy Center for the Performing Arts in Washington, D.C. has the more common American spelling "" in its references to The Eisenhower Theater, part of the Kennedy Center. Some cinemas outside New York also use the "theatre" spelling. (The word "theater" in American English is a place where both stage performances and screenings of films take place, but in British English a "theatre" is where stage performances take place but not film screenings – these take place in a cinema.)
In the United States, the spelling "theatre" is sometimes used when referring to the art form of theatre, while the building itself, as noted above, generally is spelled "theater". For example, the University of Wisconsin–Madison has a "Department of "Theatre" and Drama", which offers courses that lead to the "Bachelor of Arts in "Theatre"", and whose professed aim is "to prepare our graduate students for successful 21st Century careers in the "theatre" both as practitioners and scholars".
Some placenames in the United States use "Centre" in their names. Examples include the Stonebriar Centre mall, the cities of Rockville Centre and Centreville, Centre County and Centre College. Sometimes, these places were named before spelling changes but more often the spelling serves as an affectation. Proper names are usually spelled according to their native-variety spelling vocabulary; so, for instance, although "Peter" is the usual form of the male given name, as a surname both the spellings "Peter" and "Petre" (the latter notably borne by a British lord) are found.
For British "", the American practice varies: the "Merriam-Webster Dictionary" prefers the "-re" spelling, but "The American Heritage Dictionary of the English Language" prefers the "-er" spelling.
More recent French loanwords keep the "-re" spelling in American English. These are not exceptions when a French-style pronunciation is used ( rather than ), as with "double entendre", "genre" and "oeuvre". However, the unstressed pronunciation of an "-er" ending is used more (or less) often with some words, including "cadre", "macabre", "maître d"', Notre Dame, "piastre", and "timbre".
Commonwealth usage.
The "-re" endings are mostly standard throughout the Commonwealth. The "-er" spellings are recognized as minor variants in Canada, partly due to United States influence. They are sometimes used in proper names (such as Toronto's controversially named Centerpoint Mall).
"-ce", "-se".
For "advice"/"advise" and "device"/"devise", American English and British English both keep the noun–verb distinction both graphically and phonetically (where the pronunciation is - for the noun and - for the verb). For "licence/license" or "practice/practise", British English also keeps the noun–verb distinction graphically (although phonetically the two words in each pair are homophones with - pronunciation). On the other hand, American English uses "license" and "practice" for both nouns and verbs (with - pronunciation in both cases too).
American English has kept the Anglo-French spelling for "defense" and "offense", which are "defence" and "offence" in British English. Likewise, there are the American "pretense" and British "pretence"; but derivatives such as "defensive", "offensive", and "pretension" are always thus spelled in both systems.
Australian and Canadian usage generally follows British.
"-xion", "-ction".
The spelling "connexion" is now rare in everyday British usage, its use lessening as knowledge of Latin lessens, and it is not used at all in the US: the more common "connection" has become the standard worldwide. According to the "Oxford English Dictionary" the older spelling is more etymologically conservative, since the original Latin word had "-xio-". The American usage comes from Webster, who abandoned "-xion" and preferred "-ction". "Connexion" was still the house style of "The Times" of London until the 1980s and was still used by Post Office Telecommunications for its telephone services in the 1970s, but had by then been overtaken by "connection" in regular usage (for example, in more popular newspapers). "Connexion" (and its derivatives "connexional" and "connexionalism") is still in use by the Methodist Church of Great Britain to refer to the whole church as opposed to its constituent districts, circuits and local churches, whereas the US-majority United Methodist Church uses "Connection".
"Complexion" (which comes from "complex") is standard worldwide and "complection" is rare. However, the adjective "complected" (as in "dark-complected"), although sometimes objected to, is considered just as standard in the US as "complexioned", but is not used in this way in the UK, although there is a rare usage to mean "complicated".
In some cases, words with "old-fashioned" spellings are retained widely in the US for historical reasons (cf. connexionalism).
Greek-derived and Latin-derived spellings.
"ae" and "oe".
Many words, especially medical words, that are written with "ae/æ" or "oe/œ" in British English are written with just an "e" in American English. The sounds in question are or (or, unstressed, , or ). Examples (with non-American letter in bold): aeon", "anaemia", "anaesthesia", "caecum", "caesium", "coeliac", "diarrhoea", "encyclopaedia", "faeces", "foetal", "gynaecology", "haemoglobin", "haemophilia", "leukaemia", oesophagus", "oestrogen", "orthopaedic", "palaeontology", "paediatric", "paedophile". "Oenology" is acceptable in American English but is deemed a minor variant of "enology", whereas although "archeology" and "ameba" exist in American English, the British versions "archaeology" and "amoeba" are more common. The chemical "haem" (named as a shortening of "haemoglobin") is spelled "heme" in American English, to avoid confusion with "hem".
Canadian English mostly follows American English in this respect, although it is split on "gynecology" (e.g. Society of Obstetricians and Gynaecologists of Canada vs. the Canadian Medical Association's Canadian specialty profile of "Obstetrics/gynecology"). "Pediatrician" is preferred roughly 10 to 1 over "paediatrician", while "foetal" and "oestrogen" are similarly uncommon.
Words that can be spelled either way in American English include "aesthetics" and "archaeology" (which usually prevail over "esthetics" and "archeology"), as well as "palaestra", for which the simplified form "palestra" is described by Merriam-Webster as "chiefly Brit[ish]."
Words that can be spelled either way in British English include "encyclopaedia", "homoeopathy", "chamaeleon", "mediaeval" (a minor variant in both AmE and BrE), "foetid" and "foetus". The spellings "foetus" and "foetal" are Britishisms based on a mistaken etymology. The etymologically correct original spelling "fetus" reflects the Latin original and is the standard spelling in medical journals worldwide; the Oxford English Dictionary notes that "In Latin manuscripts both "fētus" and "foetus" are used".
The Ancient Greek diphthongs <αι> and <οι> were transliterated into Latin as <ae> and <oe>. The ligatures æ and œ were introduced when the sounds became monophthongs, and later applied to words not of Greek origin, in both Latin (for example, "cœli") and French (for example, "œuvre"). In English, which has adopted words from all three languages, it is now usual to replace "Æ/æ" with "Ae/ae" and "Œ/œ" with "Oe/oe". In many words, the digraph has been reduced to a lone "e" in all varieties of English: for example, oeconomics", "praemium", and aenigma". In others, it is kept in all varieties: for example, "phoenix", and usually "subpoena", but Phenix in Virginia. This is especially true of names: "Caesar", "Oedipus", "Phoebe", etc. There is no reduction of Latin -ae plurals (e.g., "larvae"); nor where the digraph <ae>/<oe> does not result from the Greek-style ligature: for example, "maelstrom", "toe". The British form "aeroplane" is an instance (compare other "aero-" words such as "aerosol"). The now chiefly North American "airplane" is not a respelling but a recoining, modelled after "airship" and "aircraft". The word "airplane" dates from 1907, at which time the prefix "aero-" was trisyllabic, often written "aëro-".
Commonwealth usage.
In Canada, "e" is usually preferred over "oe" and often over "ae", but "oe" and "ae" are sometimes found in academic and scientific writing as well as government publications (for example the fee schedule of the Ontario Health Insurance Plan). In Australia, "medieval" is spelt with "e" rather than "ae", as with American usage, and the "Macquarie Dictionary" also notes a growing tendency towards replacing "ae" and "oe" with "e" worldwide. Elsewhere, the British usage prevails, but the spellings with just "e" are increasingly used. "Manoeuvre" is the only spelling in Australia, and the most common one in Canada, where "maneuver" and "manoeuver" are also sometimes found.
Greek-derived spellings (often through Latin and Romance).
"-ise", "-ize" ("-isation", "-ization").
Origin and recommendations.
The "-ize" spelling is often incorrectly seen as an Americanism in Britain. It has been in use since the 15th century, predating "-ise" by over a century. "-ize" comes directly from Greek "-izein" and Latin "-izāre", while "-ise" comes via French "-iser". The "Oxford English Dictionary" () recommends "-ize" and lists the "-ise" form as an alternative.
Publications by Oxford University Press (OUP)—such as Henry Watson Fowler's "A Dictionary of Modern English Usage", "Hart's Rules", and "The Oxford Guide to English Usage"—also recommend "-ize". However, Robert Allan's "Pocket Fowler's Modern English Usage" considers either spelling to be acceptable anywhere but the US. Also, Oxford University itself does not agree with the OUP and advocates "-ise" instead of "-ize" in its staff style guide.
Usage.
American spelling avoids "-ise" endings in words like "organize", "realize" and "recognize".
British spelling mostly uses "-ise" ("organise", "realise", "recognise"), though "-ize" is sometimes used. The ratio between "-ise" and "-ize" stood at 3:2 in the British National Corpus up to 2002. The spelling "-ise" is more commonly used in UK mass media and newspapers, including "The Times" (which switched conventions in 1992), "The Daily Telegraph", "The Economist" and the BBC. The Government of the United Kingdom additionally uses "-ise", stating "do not use Americanisms" justifying that the spelling "is often seen as such". The "-ize" form is known as Oxford spelling and is used in publications of the Oxford University Press, most notably the "Oxford English Dictionary", and of other academic publishers such as "Nature", the "Biochemical Journal" and "The Times Literary Supplement". It can be identified using the IETF language tag en-GB-oxendict (or, historically, by en-GB-oed).
In Canada, the "-ize" ending is more common, whereas in Ireland, India, Australia, and New Zealand, "-ise" spellings strongly prevail: the "-ise" form is preferred in Australian English at a ratio of about 3:1 according to the "Macquarie Dictionary".
The same applies to derivatives and inflections such as "colonisation"/"colonization", or "modernisation"/"modernization".
Worldwide, "-ize" endings prevail in scientific writing and are commonly used by many international organizations, such as the United Nations Organizations (such as the World Health Organization and the International Civil Aviation Organization) and the International Organization for Standardization (but not by the Organisation for Economic Co-operation and Development). The European Union's style guides require the usage of -"ise". Proofreaders at the EU's Publications Office ensure consistent spelling in official publications such as the "Official Journal of the European Union" (where legislation and other official documents are published), but the "-ize" spelling may be found in other documents.
Exceptions.
Some verbs ending in "-ize" or "-ise" do not come from Greek "-", and their endings are therefore "not" interchangeable:
Some words spelled with "-ize" in American English are not used in British English, etc., e.g., the verb "burglarize", regularly formed on the noun "burglar", where the equivalent in British, and other versions of English, is the back-formation "burgle" and not "burglarise".
"-yse", "-yze".
The ending "-yse" is British and "-yze" is American. Thus, in British English "analyse", "catalyse", "hydrolyse" and "paralyse", but in American English "analyze", "catalyze", "hydrolyze" and "paralyze".
"Analyse" was the more common spelling in 17th- and 18th-century English. Some dictionaries of the time however preferred "analyze", such as John Kersey's of 1702, Nathan Bailey's of 1721 and Samuel Johnson's of 1755. In Canada, "-yze" is preferred, but "-yse" is also very common. In South Africa, Australia and New Zealand, "-yse" is the prevailing form.
English verbs ending in either "-lyse" or "-lyze" are not similar to the original Greek verb, which is "λύω lýo" ("I release"). Instead, they come from the noun form "lysis", with the "-ise" or "-ize" suffix. For example, "analyse" comes from French "analyser", formed by haplology from the French "analysiser", which would be spelled "analysise" or "analysize" in English.
"Hart's Rules for Compositors and Readers at the University Press, Oxford" states: "In verbs such as analyse, catalyse, paralyse, "-lys-" is part of the Greek stem (corresponding to the element "-lusis") and not a suffix like "-ize". The spelling "-yze" is therefore etymologically incorrect, and must not be used, unless American printing style is being followed."
"-ogue", "-og".
British and other Commonwealth English use the ending "-logue" while American English commonly uses the ending "-log" for words like "analog(ue)", "catalog(ue)", "dialog(ue)", "monolog(ue)", "homolog(ue)", etc. The "-gue" spelling, as in "catalogue", is used in the US, but "catalog" is more common. Additionally, in American English, "dialogue" is an extremely common spelling compared to "dialog", although both are treated as acceptable ways to spell the word (thus the inflected forms, "cataloged" and "cataloging" vs. "catalogued" and "cataloguing"). Words like "demagogue", "pedagogue", and "synagogue" are seldom used without "-ue" even in American English.
In Australia, "analog" is standard for the adjective, but both "analogue" and "analog" are current for the noun; in all other cases the "-gue" endings strongly prevail, for example "monologue", except for such expressions as "dialog box" in computing, which are also used in the UK. In Australia, "analog" is used in its technical and electronic sense, as in "analog electronics". In Canada and New Zealand, "analogue" is used, but "analog" has some currency as a technical term (e.g., in electronics, as in "analog electronics" as opposed to "digital electronics" and some video-game consoles might have an "analog stick"). The "-ue" is absent worldwide in related words like "analogy", "analogous", and "analogist".
Both British and American English use the spelling "-gue" with a silent "-ue" for certain words that are not part of the "-ogue" set, such as "tongue" (cf. tong), "plague", "vague", and "league." In addition, when the "-ue" is not silent, as in the words "argue," "ague" and "segue," all varieties of English use "-gue."
Doubled consonants.
The plural of the noun "bus" is usually "buses", with "busses" a minor American variant. Conversely, inflections of the verb "bus" usually double the "s" in British ("busses, bussed, bussing") but not American ("buses, bused, busing").
Doubled in British English.
The final consonant of an English word is sometimes doubled in both American and British spelling when adding a suffix beginning with a vowel, for example "strip/stripped", which prevents confusion with "stripe/striped" and shows the difference in pronunciation (see digraph). Generally, this happens only when the word's final syllable is stressed and when it also ends with a lone vowel followed by a lone consonant. In British English, however, a final "-l" is often doubled even when the final syllable is unstressed. This exception is no longer usual in American English, seemingly because of Noah Webster. The "-ll-" spellings are nevertheless still deemed acceptable variants by both Merriam-Webster Collegiate and American Heritage dictionaries.
Among consonants other than "l", practice varies for some words, such as where the final syllable has secondary stress or an unreduced vowel. In the United States, the spellings "kidnaped" and "worshiped", which were introduced by the "Chicago Tribune" in the 1920s, are common, but "kidnapped" and "worshipped" prevail. "Kidnapped" and "worshipped" are the only standard British spellings. However, "focused" is the predominant spelling in both British and American English, "focussed" being just a minor variant in British English.
Miscellaneous:
Doubled in American English.
Conversely, there are words where British writers prefer a single "l" and Americans a double "l". In American usage, the spelling of words is usually not changed when they form the main part (not prefix or suffix) of other words, especially in newly formed words and in words whose main part is in common use. Words with this spelling difference include
"willful", "skillful", "thralldom", "appall", "fulfill", "fulfillment", "enrollment", "installment". These words have monosyllabic cognates always written with "-ll": "will", "skill", "thrall", "pall", "fill", "roll", "stall". Cases where a single "l" nevertheless occurs in both American and British English include "null"→"annul", "annulment"; "till"→"until" (although some prefer "til" to reflect the single "l" in "until", sometimes using an apostrophe ("'til"); this should be considered a hypercorrection as "till" predates the use of "until"); and others where the connection is not clear or the monosyllabic cognate is not in common use in American English (e.g., "null" is used mainly as a technical term in law, mathematics, and computer science).
In the UK, a single "l" is generally preferred in American forms "distill", "instill", "enroll", and "enthrallment", and "enthrall", although "ll" was formerly used; these are always spelled with "ll" in American usage. The former British spellings "instal", "fulness", and "dulness" are now quite rare. The Scottish "tolbooth" is cognate with "tollbooth", but it has a distinct meaning.
In both American and British usages, words normally spelled "-ll" usually drop the second "l" when used as prefixes or suffixes, for example "full"→"useful", "handful"; "all"→"almighty", "altogether"; "well"→"welfare", "welcome"; "chill"→"chilblain".
Both the British "fulfil" and the American "fulfill" never use "-ll-" in the middle (i.e., *"fullfill" and *"fullfil" are incorrect).
Johnson wavered on this issue. His dictionary of 1755 lemmatizes "distil" and "instill", "downhil" and "uphill".
Dropped "e".
British English sometimes keeps a silent "e" when adding suffixes where American English does not. Generally speaking, British English drops it in only some cases in which it is needed to show pronunciation whereas American English only uses it where needed.
Both forms of English keep the silent "e" in the words "dyeing", "singeing", and "swingeing" (in the sense of "dye", "singe", and "swinge"), to distinguish from "dying", "singing", "swinging" (in the sense of "die", "sing", and "swing"). In contrast, the verb "bathe" and the British verb "bath" both form "bathing". Both forms of English vary for "tinge" and "twinge"; both prefer "cringing", "hinging", "lunging", "syringing".
Hard and soft "c".
A "c" is generally soft when followed by an "e", "i", or "y". One word with a pronunciation that is an exception in British English, "sceptic", is spelled "skeptic" in American English. See "Miscellaneous spelling differences" below.
Different spellings for different pronunciations.
In a few cases, essentially the same word has a different spelling that reflects a different pronunciation.
As well as the miscellaneous cases listed in the following table, the past tenses of some irregular verbs differ in both spelling and pronunciation, as with "smelt" (UK) versus "smelled" (US) (see American and British English differences: Verb morphology).
Past tense differences.
In the UK, Ireland, Australia, New Zealand and Canada, it is more common to end some past tense verbs with a "t" as in "learnt" or "dreamt" rather than "learned" or "dreamed". However, such spellings are also found in American English.
Several verbs have different past tenses or past participles in American and British English:
Miscellaneous spelling differences.
In the table below, the main spellings are above the accepted alternative spellings.
Compounds and hyphens.
British English often prefers hyphenated compounds, such as "anti-smoking", whereas American English discourages the use of hyphens in compounds where there is no compelling reason, so "antismoking" is much more common. Many dictionaries do not point out such differences. Canadian and Australian usage is mixed, although Commonwealth writers generally hyphenate compounds of the form noun plus phrase (such as "editor-in-chief"). Commander-in-chief prevails in all forms of English.
Compound verbs in British English are hyphenated more often than in American English.
Acronyms and abbreviations.
Acronyms pronounced as words are often written in title case by Commonwealth writers, but usually as upper case by Americans: for example, "Nasa / NASA" or "Unicef / UNICEF". This does not apply to abbreviations that are pronounced as individual letters (referred to by some as "initialisms"), such as "US", "IBM", or "PRC" (the People's Republic of China), which are virtually always written as upper case. However, sometimes title case is still used in the UK, such as "Pc" (Police Constable).
Contractions where the final letter is present are often written in British English without full stops/periods ("Mr", "Mrs", "Dr", "St", "Ave"). Abbreviations where the final letter is not present generally do take full stops/periods (such as "vol.", "etc.", "i.e.", "ed."); British English shares this convention with the French: "Mlle", "Mme", "Dr", "Ste", but "M." for "Monsieur". In American and Canadian English, abbreviations like "St.", "Ave.", "Mr.", "Mrs.", "Ms.", "Dr.", and "Jr.", usually require full stops/periods. Some initials are usually upper case in the US but lower case in the UK: liter/litre and its compounds ("2 L" or "25 mL" vs "2 l" or "25 ml"); and ante meridiem and post meridiem ("10 P.M." or "10 PM" vs "10 p.m." or "10 pm"). Both "AM/PM" and "a.m./p.m." are acceptable in American English, but U.S. style guides overwhelmingly prefer "a.m./p.m."
Punctuation.
The use of quotation marks, also called inverted commas or speech marks, is complicated by the fact that there are two kinds: single quotation marks (') and double quotation marks ("). British usage, at one stage in the recent past, preferred single quotation marks for ordinary use, but double quotation marks are again now increasingly common; American usage has always preferred double quotation marks, as have Canadian, Australian, and New Zealand English. It is the practice to alternate the type of quotation marks used where there is a quotation within a quotation.
The convention used to be, and in American English still is, to put full stops (periods) and commas inside the quotation marks, irrespective of the sense. British style now prefers to punctuate according to the sense, in which punctuation marks only appear inside quotation marks if they were there in the original. Formal British English practice requires a full stop to be put inside the quotation marks if the quoted item is a full sentence that ends where the main sentence ends, but it is common to see the stop outside the ending quotation marks.