Wiktionary
menthone
n. (context organic compound English) A monoterpenoid ketone that is used in perfumery etc.
Wikipedia
Menthone
Menthone is a naturally occurring organic compound with a molecular formula CHO. l-Menthone (or (2S, 5R)-trans-2-isopropyl-5-methylcyclohexanone), shown at right, is the most abundant in nature of the four possible stereoisomers. Menthone is a monoterpene and a ketone. It is structurally related to menthol which has a secondary alcohol in place of the carbonyl.
Menthone is used in perfumery and cosmetics for its characteristic aromatic and minty odor.