What do we call a lyric poem consisting of fourteen lines with a fixed rhyme scheme?

A lyric poem consisting of fourteen lines with a fixed rhyme scheme is specifically known as a sonnet. This structure and form have been prominent in poetry since the Renaissance, with two main types being the Petrarchan (or Italian) sonnet and the Shakespearean (or English) sonnet. Each type has its own distinct rhyme scheme and thematic developments.

Sonnets traditionally explore themes of love, nature, and human emotion, and their fixed structure allows for a deep exploration of these themes within a limited space. The rhyme scheme and meter provide a musical quality that enhances the emotional impact of the poem. This established form distinguishes sonnets from other types of poetry, such as ballads, odes, and epics, which do not adhere to this specific fourteen-line structure or rhyme pattern.