Quatrain

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"