A virelay is a medieval French song form, closely related to the virelai, built around a repeating refrain and a pattern of short stanzas that return to the refrain's rhyme and rhythm. In modern usage, the spelling is often treated as a variant of virelai, so the term can be confusing; some references use the two words interchangeably.
Example
Beneath the moon, the river turns and glows,
Beneath the moon, the river turns and glows;
I follow where the silver current goes,
Beneath the moon, the river turns and glows.