What do you call a line of poetry that contains five iambs?

The term for a line of poetry that contains five iambs is known as iambic pentameter. In metrical poetry, an "iamb" is a specific type of foot consisting of one unstressed syllable followed by one stressed syllable (as in "allow"). When there are five iambs in a line, it gives the line a rhythmic structure that is common in English literature, notably used by poets like Shakespeare.

The prefix "penta-" signifies five, which directly relates to the count of iambs in the meter. This specific meter allows for a natural flow and cadence that resonates well with the English language, making it a favored choice among poets for its musical quality.

The other terms listed refer to different counts of iambic feet and thus do not apply to a line with five iambs. For instance, iambic hexameter consists of six iambs, iambic tetrameter consists of four, and iambic trimeter consists of three, all of which deviate from the five iambs defining pentameter.