It is widely believed that a man's penis needs to be erect in order for him to take part in sexual intercourse and penetrate his partner's vagina and to ejaculate semen, but all are possible without an erection. The term erection is most often used to refer to an erection of the penis. An erection (pronounced ee- REK-shən) of a body part such as a man's penis, a woman's clitoris or a nipple refers to it becoming larger and harder.
