fentanylPronunciation: /ˈfɛntənʌɪl, -nɪl/Definition of fentanyl noun [mass noun] Medicine a synthetic opiate drug which is a powerful painkiller and tranquillizer. Origin: 1960s: apparently from fen- (representing phen-) + -t- + an- + -ylfentanyl in other Oxford dictionaries Definition of fentanyl in the US English dictionary
