The term for a word that has the opposite meaning of another word is "antonym." Antonyms are important in language and communication, as they allow for clearer expression and differentiation of ideas. For instance, the word "hot" has the antonym "cold," conveying contrasting concepts. Antonyms can enhance writing by providing variety and depth, enabling writers to articulate complex emotions or situations more effectively. Understanding antonyms is crucial for language learners and plays a significant role in developing vocabulary, comprehension, and critical thinking skills in communication.