Merriam-Webster Collegiate Dictionary - estradiol

 noun  Etymology: International Scientific Vocabulary estra- (from estrane parent compound of ~, from New Latin estrus + English -ane) + di- + 1-ol  Date: 1934 a natural estrogenic hormone that is a phenolic alcohol C18H24O2 secreted chiefly by the ovaries, that is the most potent of the naturally occurring estrogens, and that is administered in its natural or semisynthetic esterified form especially to treat menopausal symptoms