Definition of "progesterone" [progesterone]

• A steroid hormone, C21H30O2, secreted by the corpus luteum of the ovary and by the placenta, that acts to prepare the uterus for implantation of the fertilized ovum, to maintain pregnancy, and to promote development of the mammary glands. (noun)
• A drug prepared from natural or synthetic progesterone, used in the prevention of miscarriage, in the treatment of menstrual disorders, and as a constituent of some oral contraceptives. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "I'm not sure why the risk for endometrial cancer are mentioned in the editorial - it did not appear in the WHI results, and should not be an issue if progesterone is taken according to recommended HRT protocols."
• "He'd explain that progesterone is very similar to testosterone, so administering it tricks the brain into thinking it's swimming in the male hormone."
• "I think the biggest downside to progesterone is its name."