The American Heritage® Dictionary of the English Language, 4th Edition
n. The levorotatory form of norgestrel, used in oral contraceptives and in contraceptives implanted subdermally. In implant form it can prevent pregnancy for up to five years.
n. A synthetic progestogen used as an active ingredient in some hormonal contraceptives.
Word Usage
"However, the FDA said two recently published studies reported a greater risk of blood clots for women taking birth-control pills containing drospirenone, compared to birth-control pills containing another progestin known as levonorgestrel."