urethra, canal in most mammals that carries urine from the bladder to the outside of the body; in the male it also serves as a genital duct. The urethra is about 11/2 in. long (3.8 cm) in women, terminating above the vaginal opening. In men the urethra is about 8 in. (20 cm) long and terminates in an opening at the end of the penis. In the male the urethra is connected to the prostate gland and to the seminal vesicles and testes. It transports semen received from those organs as well as urine. See also urinary system.