Please describe the medication: levonorgestrel?

Progestin. Levonorgestrel is a progestin commonly used in oral contraceptives and the Mirena (levonorgestrel) iud. It has properties similar to progesterone.
Levonorgestrel. Levonorgestrel is used to prevent pregnancy after unprotected sexual intercourse (sex without any method of birth control or with a birth control method that failed or was not used properly [e.g., a condom that slipped or broke or birth control pills that were not taken as scheduled]). This medication is to be used as an emergency contraceptive or backup in case regular birth control fails.