What do you call a stanza or poem consisting of four lines, typically with alternate rhymes?

The term for a stanza or poem that consists of four lines, often with alternating rhymes, is known as a quatrain. Quatrains can come in various forms, including those that feature an ABAB rhyme scheme, which is common in many poetic traditions. The four-line structure allows for a concise expression of ideas, emotions, or imagery, making it a popular choice among poets.

In contrast, a couplet refers to a pair of lines that often rhyme and have the same meter, while an octet is a stanza or poem made up of eight lines, typically following a specific rhyme scheme. The broader term 'stanza' can refer to any grouping of lines in a poem, making it too general to specifically indicate a four-line format. Thus, 'quatrain' specifically captures the essence of a four-line stanza with the characteristic features of rhyme.