What do you call a poem that consists of 14 lines?

A poem that consists of 14 lines is specifically known as a sonnet. This type of poem traditionally explores themes such as love, nature, and mortality and follows a specific structure. There are different forms of sonnets, with the most notable being the Petrarchan (or Italian) and the Shakespearean (or English) sonnet. The Petrarchan sonnet typically has an octave and a sestet, while the Shakespearean sonnet consists of three quatrains followed by a couplet, all adhering to a specific rhyme scheme.

The other forms mentioned, such as odes, lyrics, and ballads, do not have the defining characteristic of a 14-line structure. Odes are often lengthy and elevate a particular subject, lyrics express personal thoughts and feelings, and ballads are narrative poems that often tell a story, usually in a structured stanza format, but none of them are limited to the 14 lines that characterize sonnets.