pyrazolone

noun
py·​raz·​o·​lone | \ -ˌlōn How to pronounce pyrazolone (audio) \

Medical Definition of pyrazolone

1 : any of three isomeric carbonyl compounds C3H4N2O derived from pyrazoline
2 : any of various derivatives of the pyrazolones some of which (as antipyrine) have been used as analgesics and antipyretics