enantiomerPronunciation: /ɪˈnantɪə(ʊ)mə, ɛ-/Definition of enantiomer noun Chemistry each of a pair of molecules that are mirror images of each other. Derivatives enantiomericPronunciation: /-ˈmɛrɪk/ adjective enantiomerically adverb Origin: 1930s: from Greek enantios 'opposite' + -merenantiomer in other Oxford dictionaries Definition of enantiomer in the US English dictionary