Final answer:
A refrain is the repetition of a word or phrase at the end of several clauses to emphasize an important theme or idea.
Step-by-step explanation:
The repetition of a word or phrase at the end of several clauses is called a refrain. A refrain is a powerful rhetorical device that is often used in prose, poetry, and speeches to emphasize an important theme or idea. For example, in Martin Luther King Jr.'s famous speech, he repeated the phrase 'I have a dream' throughout the text as a refrain to highlight the vision of equality and justice.