"masturbation," 1727, from Onan, son of Judah (Gen. xxxviii.9), who spilled his seed on the ground rather than impregnate his dead brother's wife: "And Onan knew that the seed should not be his; and it came to pass, when he went in unto his brother's wife, that he spilled it on the ground, lest that he should give seed to his brother." Somehow this was twisted by prudes into a prohibition of masturbation.
Main Entry: onan·ism Pronunciation: 'O-n&-"niz-&m Function: noun 1:MASTURBATION 2:COITUS INTERRUPTUS —onan·is·tic/"O-n&-'nis-tik/adjective Onan/'O-n&n/, Biblical character. In the Book of Genesis Onan was commanded by his father to impregnate the widow of hisslain brother and to raise the offspring of the union. In order to avoid raising descendants for his late brother, however, Onan engaged in coitus interruptus.