An "antonyme" is a word that has the opposite meaning of another word. For example, the word hot is an antonym of cold. Antonyms help us understand language better by providing contrast, making it easier to express different ideas and emotions. In language, antonyms can be categorized into different types, such as gradable antonyms, which show varying degrees of difference, like big and small. Another type is complementary antonyms, where one term negates the other, such as alive and dead. Understanding antonyms enriches vocabulary and enhances communication skills.