noun
also oes·trone ˈeˌstrōn
( -s )
Etymology: International Scientific Vocabulary estr in, oestr in + -one
: a white crystalline estrogenic hormone that is a phenolic steroid ketone C 18 H 22 O 2 usually obtained from the urine of pregnant females (as mares or women) and that is used similarly to estradiol — called also theelin