What term describes words that have similar meanings?

The term that describes words that have similar meanings is "synonyms." Synonyms are words that can often be used interchangeably in a given context because they convey similar ideas. For example, "happy" and "joyful" are synonyms because they both express a similar feeling of contentment.

The other terms refer to different concepts. Antonyms are words with opposite meanings, such as "hot" and "cold." Prefixes are syllables added at the beginning of a word to alter its meaning, like "un-" in "unhappy." Suffixes are syllables added at the end of a word for similar purposes, such as "-ness" in "happiness." Understanding these distinctions helps clarify the specific meanings and roles of different types of words in language.