A sememe is a basic unit of meaning in linguistics. It refers to the smallest unit of meaning in language, which is not further divisible into any smaller parts. While there aren't many true synonyms for sememe, there are related terms in linguistics that refer to similar concepts. For example, the term "morpheme" is often used interchangeably with sememe, referring to the smallest unit of meaning in a language that cannot be further divided. Another related term is "lexeme," which refers to the smallest unit of language that can express an independent meaning, such as a word or part of a word.