prōˈjestəˌrōn noun
( -s )
Etymology: proge rtin + ster ol + -one
: a crystalline ketonic steroid progestational hormone C 21 H 30 O 2 that is obtained from corpus luteum or made synthetically, that is regarded as a biological precursor of corticoid and androgenic hormones, and that is used chiefly in treating functional uterine bleeding; 4-pregnene-3,20-dione