Identifying the use or function of an object, item, or idea is also a short way of defining. We may think we already know the use and function of most of the things we interact with regularly.
The text says that defining through synonyms, antonyms, and etymology helps audiences better understand concepts. I connected this to how English teachers often explain new vocabulary by using familiar words or their origins. Learning that “assassin” came from “hashish-eater” makes the concept more memorable than just a dictionary definition. This shows how history and language can make information stick with an audience.