late 14c., from O.Fr. refrain, alteration of refrait, properly pp. of refraindre "repeat," also "break off," from Prov. refranhar "singing of birds, refrain," from V.L. *refrangere "break off," alteration of L. refringere (see refraction
). The notion is of something that
causes a song to "break off" then resume. Not common before 19c.