-ˌlōn noun
( -s )
Etymology: International Scientific Vocabulary pyrazole + -one
1. : any of three isomeric carbonyl compounds C 3 H 4 N 2 O derived from pyrazoline
2. : any of numerous derivatives of the pyrazolones some of which (as antipyrine) are used as analgesics and antipyretics and others (as 3-methyl-1-phenyl-5-pyrazolone) in making azo dyes and as developers