1. To use a phrase, verse, or group of verses repeated at intervals throughout a song or poem; especially, at the end of each stanza.
2. Etymology: from Old French refrain, alteration of refrait, from refraindre "to repeat" also "to break off"; from Provençal (Romance language of several dialects in southern France) refranhar, "singing of birds, refrain", from Vulgar Latin refrangere, "to break off", an alteration of Latin refringere, "to break".

The Vulgar Latin mentioned above was the everyday or common speech of the Roman people, as opposed to literary Latin.