: the male copulatory organ of a higher vertebrate animal that in mammals including humans usually functions as the channel by which urine leaves the body and is typically a cylindrical organ that is suspended from the pubic arch, contains a pair of large lateral corpora cavernosa and a smaller ventromedial corpus cavernosum containing the urethra, and has a terminal glans enclosing the ends of the corpora cavernosa, covered by mucous membrane, and sheathed by a foreskin continuous with the skin covering the body of the organ
Illustration of PENIS
Male sex organ, which also provides the channel for urine to leave the body. Three long columns of tissue extend through its length, covered by elastic tissue and a thin layer of skin. One expands at the tip into a mushroom-shaped structure (glans penis) and contains the urethra (seeurinary system), which ends in a slitlike opening. In sexual arousal, blood fills spaces in the tissue, and blood vessels constrict to hold it there, enlarging and hardening the penis in an erection. The foreskin, a circular fold of skin covering the glans, is often removed (seecircumcision). See alsoreproductive system.