What does "virelay" mean?

Virelay: An ancient French song, or short poem, wholly in two rhymes, and composed in short lines, with a refrain. Of such matter made he many lays, Songs, complains, roundels, virelayes. Chaucer. To which a lady sung a virelay. Dryden. Note: "The virelay admitted only two rhymes, and, after employing one for some time, the poet was virer, or to turn, to the other." Nares.