What term refers to discussing one thing in terms of another closely related thing?

The term that refers to discussing one thing in terms of another closely related thing is metonymy. Metonymy involves substituting the name of one thing with the name of something else that is closely associated with it. This figure of speech enriches language by allowing the description of concepts through their associations, enhancing understanding and vividness in communication.

For instance, using "the White House" to refer to the U.S. presidency or the administration is a classic example of metonymy, as it relates to the building where presidential decisions are made rather than the individuals themselves. This relationship allows for a more concise and impactful expression of ideas.

In contrast, a metaphor draws a direct comparison between two unrelated things, while synecdoche involves using a part of something to represent the whole or vice versa. An antonym, on the other hand, refers to words that have opposite meanings and does not apply to the concept of discussing one entity in terms of another related one.