What term describes extreme exaggeration used for emphasis?

The term that describes extreme exaggeration used for emphasis is hyperbole. Hyperbole is a figure of speech that involves making exaggerated claims or statements that are not meant to be taken literally. It is often used in literature, poetry, and everyday language to create a strong impression or to emphasize a particular point. For example, saying "I've told you a million times" is an instance of hyperbole, as the speaker does not literally mean they have said it a million times but uses the exaggeration to stress their frustration.

In contrast, a metaphor provides a direct comparison between two unrelated things, suggesting that one thing is another to highlight a similarity, rather than exaggerating a point. A simile, on the other hand, also makes comparisons but does so using "like" or "as." An idiom is a phrase that has a figurative meaning different from its literal meaning, like "kick the bucket," which means to die, but does not involve exaggeration for emphasis.