es·tra·di·ol (?s?tr?-d??ôl?, -?l?, -?l?)n. An estrogenic hormone, C18H24O2, that is produced by the ovaries and is the dominant naturally occurring estrogen in women between puberty and menopause. It is used to treat menopausal symptoms and other conditions.[estra-, estrogenic hormone (from estrus) + di- + -ol.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.estradiol (??str??da??l; ?i?str?-) n (Biochemistry) the US spelling of oestradiolCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014es?tra?di?ol (??s tr??da? ?l, -?l) n. an estrogenic hormone, C18H24O2, produced by the maturing Graafian follicle, that causes proliferation and thickening of the tissues and blood vessels of the endometrium, used medically in the treatment of estrogen deficiency and certain menopausal conditions. [1930?35; estra(ne) a component of estrone] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.