What are the conditions for adultery to occur, and is a man's masturbating by placing his penis in a woman's mouth considered adultery?

The adultery that necessitates the prescribed punishment (the hadd) is the insertion of the male organ's head into a forbidden and naturally desirable vagina, without any semblance of a marriage contract, even if there is no ejaculation. This is established by confession or the testimony of four witnesses. As for a man masturbating by placing his organ on a foreign woman's mouth or any other part of her body, it is strictly forbidden, a grave abomination, and a clear sin. It is considered a form of fornication that does not necessitate the prescribed punishment.