Catalectic

A catalectic line is a metrically incomplete line of verse, lacking a syllable at the end or ending with an incomplete foot. One form of catalexis is headlessness, where the unstressed syllable is dropped from the beginning of the line.
A line missing two syllables is called brachycatalectic.
In English.
Poems can be written entirely in catalectic lines, or entirely in acatalectic (complete) lines, or a mixture, as the following carol, composed by Cecil Frances Alexander in 1848:
It has been argued that across a number of Indo-European languages, when the two types of line are mixed in this way, the shorter line tends to be used as a coda at the end of a period or stanza.
Blunt and pendant catalexis.
It has been argued that catalexis can be divided into two types. (Here "x" stands for an "anceps" syllable.)
An example of a blunt line becoming pendant in catalexis is Goethe's poem Heidenröslein, or, in the same metre, the English carol Good King Wenceslas:
Another example is the children's song Here We Go Round the Mulberry Bush, of which the first stanza ends as follows:
In all of these songs, when they are set to music, there is a lengthening of the penultimate syllable in order to equalise the two lines. However, there is not enough evidence to tell if a similar phenomenon occurred in Ancient Greek.
When a poem is doubly catalectic (brachycatalectic), that is, shortened by two syllables, a blunt ending remains blunt:
Quantitative metres.
In languages which use quantitative metres, such as Latin, Ancient Greek, Arabic, Persian, and Sanskrit, the final syllable of any line is "anceps", that is, indifferently long or short. According to one view dating back to ancient times, even if the final syllable is prosodically short, it counts as long because of the pause which follows it (see brevis in longo). Thus any line ending – u –, when catalectic, becomes – x.
An example in Ancient Greek is the iambic tetrameter, which in normal and catalectic form is as follows:
In classical Arabic, the most commonly used metre, the "ṭawīl", has normal and catalectic forms as follows:
A similar phenomenon is also found in classical Persian. For example, the metre based on the choriamb pattern (– u u –) has a shortened form as follows:
Catalexis in Greek poetry.
Catalexis was common in Greek and Latin meter, and also in ancient Sanskrit verse. Catalectic endings are particularly common where the rhythm of the verse is dactylic ( – u u ), trochaic ( – u ), or anapestic ( u u – ); they tend to be associated with the end of a strophe or period, so much so that it can almost be said that acatalectic forms cannot end a period. In classical verse, the final syllable of a line always counted as long, so that if a dactyl ( – u u ) is made catalectic, it becomes a spondee ( – – ).
Ancient poetry was often performed to music, and the question arises of what music accompanied a catalectic ending. A few ancient Greek poems survive with authentic musical notation. Four of these are by Mesomedes (early 2nd century CE). Secondary sources of Mesomedes' poems To Helios and To Nemesis are in a catalectic meter known as apokrota "sonorous." In each case, in place of the missing short element of the text (i.e., missing syllable) one often finds lengthening signs. In two cases in To Helios, this appears to be a three-note melisma. It is possible ancient use of catalexis indicated some form of melody or continued singing in place of the missing syllables.
In ancient Greek drama, catalectic meters may have been associated with a male aulete or had some other special use. For example, of Menander's surviving plays, almost all are in iambic trimeters. He changed the meter in one long scene in Misanthrope to 15-syllable catalectic iambic tetrameter recited to an aulos accompaniment.
Catalexis in Latin poetry.
Poem 25 by Catullus is in iambic tetrameter catalectic. Of Catullus' extant 114 or so poems and fragments, this meter appears only in this poem.
Catalexis in music.
Venantius Fortunatus' hymn "Pange lingua" is in trochaic tetrameter catalectic—the meter of the marching chants of the Roman armies. The hymn is one of the oldest with surviving musical notation.
As Greek meter is often used to describe musical phrasing, some famous themes include: