from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Any of a class of cyclic chemical compounds that contain an unsaturated six-membered ring with two double bonds, one oxygen atom and a ketone functional group.
from the GNU version of the Collaborative International Dictionary of English
- n. An unsaturated cyclic compound, C5H4O2, of which two varieties are known, α and γ. γ-pyrone is the parent substance of several natural yellow dyestuffs.
from The Century Dictionary and Cyclopedia
- n. A crystalline ketonic compound, C5H4O2, made by heating chelidonic acid. It melts at 32.5° C.
pyro- + -one (Wiktionary)