A foot consisting of a short syllable followed by a long one, as in ãmans, or of an unaccented syllable followed by an accented one, as invent; an iambic. See the Couplet under Iambic, n.

(OALD) metrical foot in poetry consisting of one short or unstressed syllable followed by one long or stressed syllable.

a metrical unit with unstressed-stressed syllables