Meter & Rhythm
Truncation
From Latin truncare: to cut short. Truncation at the line's end creates a clipped, emphatic effect; it is sometimes called 'headless' when applied to the line's beginning.
Definition
The omission of one or more syllables from the expected end of a metrical line — a synonym for catalexis.
Example
A trochaic tetrameter line ending with only 7 syllables (instead of 8) is truncated: the final unstressed syllable is cut.