IAMBUS
iamb, iambus
(noun) a metrical unit with unstressed-stressed syllables
Source: WordNet® 3.1
Etymology
Noun
iambus (plural iambuses or iambi)
(poetry) an iamb
Source: Wiktionary
I*am"bus, n.; pl. L. Iambi, E. Iambuses. Etym: [L. iambus, Gr. jacere
to throw. Cf. Jet a shooting forth.] (Pros.)
Definition: A foot consisting of a short syllable followed by a long one,
as in âmans, or of an unaccented syllable followed by an accented
one, as invent; an iambic. See the Couplet under Iambic, n.
Source: Webster’s Unabridged Dictionary 1913 Edition