-onym

The suffix -onym (from / name) is a bound morpheme, that is attached to the end of a root word, thus forming a new compound word that designates a particular "class" of names. In linguistic terminology, compound words that are formed with suffix -onym are most commonly used as designations for various onomastic classes. Most onomastic terms that are formed with suffix -onym are classical compounds, whose word roots are taken from classical languages (Greek and Latin).
For example, onomastic terms like toponym and linguonym are typical classical (or neoclassical) compounds, formed from suffix "-onym" and classical (Greek and Latin) root words ( / place; / language). In some compounds, the "-onym" morpheme has been modified by replacing (or dropping) the "o". In the compounds like "ananym" and "metanym", the correct forms ("anonym" and "metonym") were pre-occupied by other meanings. Other, late 20th century examples, such as "hypernym" and "characternym", are typically incorrectly formed neologisms, for which there are more traditional words formed in "-onym" ("hyperonym" and "charactonym").
The English suffix "-onym" is from the Ancient Greek suffix ("ōnymon"), neuter of the suffix ("ōnymos"), having a specified kind of name, from the Greek ("ónoma"), Aeolic Greek ὄνυμα ("ónyma"), "name". The form "-ōnymos" is that taken by "ónoma" when it is the end component of a bahuvrihi compound, but in English its use is extended to tatpurusa compounds.
The suffix is found in many modern languages with various spellings. Examples are: Dutch "synoniem", German "Synonym", Portuguese "sinónimo", Russian синоним ("sinonim"), Polish "synonim", Finnish "synonyymi", Indonesian "sinonim", Czech "synonymum".
According to a 1988 study of words ending in "-onym", there are four discernible classes of "-onym" words: (1) historic, classic, or, for want of better terms, naturally occurring or common words; (2) scientific terminology, occurring in particular in linguistics, onomastics, etc.; (3) language games; and (4) nonce words. Older terms are known to gain new, sometimes contradictory, meanings (e.g., "eponym" and "cryptonym"). In many cases, two or more words describe the same phenomenon, but no precedence is discernible (e.g., "necronym" and "penthonym"). New words are sometimes created, the meaning of which duplicating existing terms. On occasion, new words are formed with little regard to historical principles.