IUD, also known as intrauterine device, is a contraceptive device that is inserted into a woman's uterus. There are several synonyms for the word IUD, including intrauterine system (IUS), coil, and long-acting reversible contraceptive (LARC). The term IUS is often used interchangeably with IUD and refers to a hormonal intrauterine device. The coil is another commonly used synonym for IUD, as it refers to the spiral-shaped design of the device. LARC is a broader term that includes other long-acting contraceptive methods, such as implants. Regardless of the phrase used, IUDs are a safe and effective form of birth control that can prevent pregnancy for years at a time.