diaphorasePronunciation: /dʌɪˈafəreɪz/Definition of diaphorase noun [mass noun] Biochemistry an enzyme of the flavoprotein type, able to oxidize a reduced form of the coenzyme NAD. Origin: 1930s: from Greek diaphoros 'different' + -asediaphorase in other Oxford dictionaries Definition of diaphorase in the US English dictionary