idemEnglishOxford New American Dictionaryidem /ˈīˌdem, , ˈaɪˌdɛm , ˈiˌdem, ˈɪˌdɛm / ▸ adverb used in citations to indicate an author or work that has just been mentioned: Marianne Elliott, Partners in Revolution, 1982; idem, Wolfe Tone, 1989. – ORIGIN Latin, ‘the same’.