Refrain is an interesting English word.
It holds two distinct possibilities of interpretation. One, it could mean – “abstain; hold back” – as in “refrain from attacking”. This comes from the Latin word, refrēnāre, which means to check with a bridle.
The other interpretation is, as in music, that of a much repeated idea (or line or verse) . Refrain is something that sticks to your mind by virtue of emphasis and repetition. This comes from Old Frenc, and ultimately from the Latin word refringere, which means “to break into pieces”.
So the next time someone tells you “Refrain”, you should say “How do you mean ?”