Synonym

n. word which has the same or almost the same meaning as another

Synonyms (in ancient Greek, συν ("syn") = plus and όνομα ("onoma") = name) are different words with identical or at least similar meanings. Words that are synonyms are said to be synonymous, and the state of being a synonym is called synonymy.An example of synonyms are the words car and automobile. Similarly, if we talk about a long time or an extended time, long and extended become synonyms. In the figurative sense, two words are often said to be synonymous if they have the same connotation:"a widespread impression that … Hollywood was synonymous with immorality" (Doris Kearns Goodwin)
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Noun
1. two words that can be interchanged in a context are said to be synonymous relative to that context
(synonym) equivalent word
(hypernym) word

n. synonym, word having the same or a similar meaning as another

adv. synonymously, in a synonymous manner, with the same meaning

adj. synonymous, having the same meaning, equivalent, similar, identical

(n.)
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.