Definitions for villanelleˌvɪl əˈnɛl
Random House Webster's College Dictionary
a short poem of fixed form, written in tercets, usu. five in number, followed by a final quatrain, all being based on two rhymes.
Origin of villanelle:
1580–90; < F < It; see villanella
a type of poetry, consisting of five tercets and one quatrain, with only two rhymes.
a poem written in tercets with but two rhymes, the first and third verse of the first stanza alternating as the third verse in each successive stanza and forming a couplet at the close