What is a fourteen-line poem with a specific rhyme scheme called?

A fourteen-line poem with a specific rhyme scheme is called a Shakespearean sonnet. This form traditionally consists of three quatrains followed by a final couplet, and its rhyme scheme is typically ABABCDCDEFEFGG.

The structure allows for a development of a theme or argument in the quatrains, culminating in a resolution or turn in the final couplet. This poetic form has been highly influential in English literature, particularly through the works of William Shakespeare, which often explore themes of love, time, and beauty. In contrast, a haiku is a three-line poem focused on nature, a limerick is a five-line humorous poem with a distinct rhythm and rhyme scheme, and a quatrain is simply a stanza or poem containing four lines, which does not necessarily include the fourteen-line requirement.