in prosody, the metrical system that is most commonly used in English poetry. It is based on both the number of stresses, or accents, and the number of syllables in each line of verse. A line of iambic pentameter (pentameter) verse, for example, consists of five feet, each of which is an iamb (an unstressed followed by a stressed syllable). Although accentual-syllabic verse is very strictly measured, variations in both accent placement and the number of syllables are often allowed.