Overview
A refrain (from Vulgar Latin refringere, "to repeat", and later from Old French refraindre) is the line or lines that are repeated in music or in poetry — the "chorus" of a song. Poetic fixed forms that feature refrains include the villanelle, the virelay, and the sestina.
In popular music, the refrain or chorus may contrast with the verse melodically, rhythmically, and harmonically; it may assume a higher level of dynamics and activity, often with added instrumentation. Chorus form, or strophic form, is a sectional and/or additive way of structuring a piece of music based on the repetition of one formal section or block played repeatedly.
Usage in history
In music, a refrain has two parts: the lyrics of the song, and the melody. Sometimes refrains vary their words slightly when repeated; recognizability is given to the refrain by the fact that it is always sung to the same tune, and the rhymes, if present, are preserved despite the variations of the words. Such a refrain is featured in "The Star-Spangled Banner", which contains a refrain which is introduced by a different phrase in each verse, but which always ends:
O'er the land of the free, and the home of the brave.
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