A four-syllable foot.
A four-line stanza, rhyming
- abac or abcb (unbounded, or ballad), as in "Sir Patrick Spence" and Samuel Taylor Coleridge's "The Rime of the Ancient Mariner"
- aabb (a double couplet),
- abab (interlaced, alternate, or heroic), as in Thomas Gray's "Elegy Written in a Country Churchyard"
- abba (envelope or enclosed), as in Alfred Lord Tennyson's "In Memoriam"
- aaba, the stanza of Edward Fitzgerald's "The Rubáiyát of Omar Khayyám"