Answer:
A refrain.
Step-by-step explanation:
A refrain is a line or lines that are repeated throughout the poem that, one repetition after the other, builds upon several meanings of the line that together bring deeper sense to the refrain. The word comes from Latin and it literally means “to repeat”. Refrains can also be used in the context of music, and, in rough terms, they can be equated with what is known as the “chorus” in a pop song, for example.