Which term describes the repetition of a word or phrase for effect?

The term that describes the repetition of a word or phrase for effect is anaphora. This rhetorical device is often used in writing and speech to create a sense of rhythm and to emphasize a particular idea or emotion. By repeating a specific word or phrase at the beginning of successive clauses or sentences, the speaker can enhance their message and make it more memorable.

In various forms of literature and speeches, anaphora serves to underscore the significance of concepts and to engage the audience more effectively. For instance, a famous example of anaphora can be seen in Martin Luther King Jr.'s "I Have a Dream" speech, where he repeatedly emphasizes the phrase "I have a dream" to convey the vision of equality and freedom.

The other terms listed have distinct meanings unrelated to repetition for effect. Allusion refers to a brief and indirect reference to a person, place, thing, or idea of historical, cultural, literary, or political significance. Understatement is a figure of speech employed to intentionally make a situation seem less important than it is. Metaphor, on the other hand, involves a comparison between two unlike things by stating one is the other, enriching language through analogy but not involving repetition as a primary characteristic.