Qualité des mots synonymes.
ETYM Latin synonymia, Greek, a synonym: cf. French synonymie.
The semantic relation that holds between two words that can (in a given context) express the same meaning; SYN. synonymity, synonymousness.
Near or identical meaning between or among words. There are very few strict synonyms in any language, although there may be many near-synonyms, depending upon the contexts in which the words are used. Thus brotherly and fraternal are synonyms in English, but a brotherhood is not the same as a fraternity. People talk about the brotherhood of man but seldom if ever about the “fraternity of man”. Brotherhood and fraternity are not therefore strictly synonymous.