Which word refers to an exaggerated or grotesque imitation, often used to mock or ridicule?

The term that best fits the definition of an exaggerated or grotesque imitation used to mock or ridicule is "travesty." A travesty often involves taking a serious subject or a recognized style and transforming it into a caricature, stripping it down to its absurd or ridiculous elements. This is typically done in a way that highlights the flaws or weaknesses in the original work or concept, serving as both a critique and a form of humor.

In contrast, while "parody" also involves imitation and mocking, it often maintains a degree of fondness or playful homage to the original work, without the same level of grotesque exaggeration. "Imitation" is a broader term that does not necessarily carry the connotation of ridicule or exaggeration. Lastly, "satire" involves using humor, irony, or exaggeration as a means of criticism, but it does not exclusively refer to grotesque imitation. Together, these nuances clarify why "travesty" is the most fitting answer in this context.