Refrain

At first sight, everyone knows what a refrain is, and one might think that its definition is not difficult. The ancient rhetoricians were mainly concerned with distinguishing the types and uses of refrains but in general they did not dwell on the features that allow us to designate it as such. Once it is accepted that the three criteria of repetition, interval, and immutability have been, then everything seems to be said. The refrain repeats a word, a phrase or a melody identically and at a certain interval. If one of these three criteria is missing, it would no longer be a refrain: without the identity, we would have a varied repeat, and without the interval, we would have a ostinato, or at least a duplication.