What word refers to a term that means the opposite of another?

The term that means the opposite of another word is "antonym." This is a fundamental concept in vocabulary and language studies. For instance, the antonym of the word "hot" is "cold," and understanding antonyms is essential for building a rich vocabulary. Antonyms help in expressing contrast and enhancing clarity in communication, making it easier to convey different meanings.

In contrast, an adverb modifies verbs, adjectives, or other adverbs, and doesn't relate to opposites. A synonym refers to a word that has the same or nearly the same meaning as another word, so it also does not fit the definition of opposites. An adjective is a word that describes a noun but does not imply any relationship to the concept of opposites. Therefore, "antonym" is indeed the appropriate term to identify words that have opposite meanings.