Refrain is a repeating verse that closes a stanza or their group. There may be several. Different dictionaries give several other interpretations of this term, and we will consider them below.
Rondo
According to the explanatory dictionary of Efremova, refrain is a part of a certain vocal work that has a couplet form. This fragment is repeated in a constant form and acts as a refrain. Also, this source indicates that the play with refrain is called "rondo". In this case, the indicated fragment is repeated many times, alternating with various episodes.
Poem
Now consider the interpretations that are given in the Small Academic Dictionary. In literature, refrain is a verse or their group, which is repeated within the framework of one work. In music, this concept is responsible for a fragment of a vocal unit of a couplet form, which is repeated in a constant form and is a refrain. In the work “What to Do” by Chernyshevsky, a brisk, bold song with a cheerful melody with two or three sad notes that disappear and disappear in the final couplet is mentioned in the refrain.
Couplet
Now let's look at the interpretation that is given in the “Dictionary of Foreign Terms of the Russian Language”. According to this source, refrain is the repetition of the same words after each verse or stanza. It can also be called a refrain (that is how the word refrain is translated from French). A similar definition is also given in the “Explanatory Dictionary of Kuznetsov”. In this case we are talking about a poem or their group, which is repeated in a song or poem. In the first case, it is called a chorus. This term is also used if they want to indicate the frequent repetition of something the same. As a rule, refrain is included in the work at least three times. There is a similar definition in the explanatory dictionary of Ozhegov.