An antonym is a word that has the opposite meaning of another word. For example, "hot" and "cold" are antonyms, as are "good" and "bad". Antonyms can be all types of words: verbs, nouns, adjectives, adverbs, and more. There are different types of antonyms, including complementary antonyms, gradable antonyms, and relational antonyms. Complementary antonyms are word pairs where the positive use of one means the negative use of the other, such as "on" and "off". Gradable antonyms are word pairs where one word is the opposite of the other, but there are degrees of difference between them, such as "hot" and "warm". Relational antonyms are word pairs where one word describes a relationship between two objects, and the other word describes the same relationship but with the objects in the opposite order, such as "parent" and "child". Antonyms are closely related to synonyms, which are words that have identical meanings.