iamb

n. (Poetry) iambus, foot consisting of two syllables (the first syllable is long and the second short or the first syllable is stressed and the second unstressed)

For other senses of the words "iamb" or "iambic", see iamb (disambiguation).An iamb or iambus is a metrical foot used in various types of poetry. Originally the term referred to one of the feet of the quantitative meter of classical Greek prosody: a short syllable followed by a long syllable (as in i-amb). This terminology was adopted in the description of accentual-syllabic verse in English, where it refers to a foot comprising an unstressed syllable followed by a stressed syllable (as in a-bove).
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Noun
1. a metrical unit with unstressed-stressed syllables
(synonym) iambus
(hypernym) metrical foot, foot, metrical unit

(n.)
An iambus or iambic.
  

metr. iamb(us)