ˈpīˌrōn noun
( -s )
Etymology: International Scientific Vocabulary pyr- + -one
1. : either of two isomeric carbonyl compounds C 5 H 4 O 2 derived from pyran:
a. : an oily liquid delta-lactone; 2 H -pyran-2-one — called also alpha-pyrone, 2-pyrone ; compare coumalin , coumarin
b. : a hygroscopic crystalline compound; 4 H -pyran-4-one — called also gamma-pyrone, 4-pyrone ; compare chromone; structural formula
2. : a derivative of either of the pyrones