noun

• (American spelling, biochemistry, pharmacology) A natural estrogenic hormone that is a phenolic alcohol estra-1,3,5-triene-3,17-diol (C₁₈H₂₄O₂) secreted chiefly by the ovaries of all vertebrates, that is a major and the most potent of the naturally occurring estrogens; the semisynthetic esterified compound is used medicinally to treat estrogen deficiency and breast cancer.