(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.

plural of estradiol

(organic chemistry, pharmacology) The estradiol ester of valeric acid that is an estradiol medication - C₂₃H₃₂O₃.