One of two or more words (commonly words of the same language) which are equivalents of each other; one of two or more words which have very nearly the same signification, and therefore may often be used interchangeably. See under Synonymous.
- A word having the same or nearly the same meaning as another word or other words in a language.
- A word or an expression that serves as a figurative or symbolic substitute for another.
- Biology A scientific name of an organism or of a taxonomic group that has been superseded by another name at the same rank.