It is a five line stanza, varied in rhyme and line, usually of the with the rhyme scheme ababb. An example of cinquain is the following stanza from Percy Bysshe Shelley's "To a Skylark":

Teach me half the gladness -A-
That thy brain must know, -B-
Such harmonious madness -B-
From my lips would flow -A-
The world should listen then, as I am listening now. -B-
(B lines rhyme with other B lines, and A lines rhyme with other B lines. This poems last line may not precisely fit this pattern.)