pregˈnēn ə lˌōn noun
( -s )
Etymology: International Scientific Vocabulary pregnene + -ol + -one
: a crystalline unsaturated hydroxy steroid ketone C 21 H 32 O 2 formed by the oxidation of cholesterol (as in living cells), stigmasterol, diosgenin, or other steroids and yielding progesterone on dehydrogenation; 3-hydroxy-5-pregnen-20-one