synonymousPronunciation: /sɪˈnɒnɪməs/Translate synonymous | into French | into German | into Italian | into Spanish Definition of synonymous adjective 1(of a word or phrase) having the same meaning as another word or phrase in the same language. 2closely associated with or suggestive of something:his deeds had made his name synonymous with victoryDerivatives synonymously adverb synonymousness noun synonymous in other Oxford dictionaries Definition of synonymous in the US English dictionary