An iamb is a two-syllable metrical pattern used in poetry in which the first syllable is unstressed and the second syllable is stressed. “Attain,” and “define” show the iambic pattern of unstressed and stressed syllables. In English poetry, metrical patterns are called feet, so an iamb is a type of foot.
The most common metrical foot in English poetry is the iamb. It means that an unstressed syllable is followed by a stressed one, short syllable is followed by a long one.
