Priapism (Greek Priapismus on behalf of Priapus - the ancient Greek deity of fertility, an analogue of the Roman god Faun) is a painful condition based on a persistent increase in the volume of the penis due to long-term (more than 4 hours) preservation of an erection. In other words, an inadequately prolonged erection that is maintained even in the absence of stimulation. Priapism is also called forced prolongation of sexual intercourse. Also, priapism is the name given to one of the most popular forms of masturbation - masturbation.