Quinzaine is an unrhymed verse

Verse (poetry)

A verse is formally a single line in a metrical composition, e.g. poetry. However, the word has come to represent any division or grouping of words in such a composition, which traditionally had been referred to as a stanza....

 of fifteen syllable

Syllable

A syllable is a unit of organization for a sequence of speech sounds. For example, the word water is composed of two syllables: wa and ter. A syllable is typically made up of a syllable nucleus with optional initial and final margins .Syllables are often considered the phonological "building...

s. The word comes from the French word quinze, meaning fifteen. The syllables are distributed over three lines so that there are seven syllables in the first line, five in the second line, and three in the third line (7/5/3). The first line makes a statement. The next two lines ask a question relating to that statement.