Which term best defines the use of exaggeration to criticize?

The term that best defines the use of exaggeration to criticize is satire. Satire is a literary technique that employs humor, irony, and exaggeration to highlight and criticize societal flaws, behaviors, or institutions. It aims to provoke thought and often calls attention to issues that need to be addressed, using exaggeration as a tool to express the absurdity or extreme nature of certain situations.

In the context of literature and social commentary, satire allows writers to craft sharp critiques of various subjects, making complex or serious ideas more accessible and engaging through exaggerated portrayals. This method can encourage reflection and discussion about the topics being addressed.

The other terms mentioned represent different literary devices: similes and metaphors focus on comparisons, while metonymy involves substituting the name of one thing with something closely associated with it. These concepts do not inherently involve the critical edge that satire embodies.