For a man not to have intercourse with a married woman. Theocratic Law forbids a woman from having multiple husbands, and therefore any relations between a married woman and another man are forbidden under this commandment. Both adulterers, the man and the woman, would face capital punishment.
Since a man is permitted by the basic Torah Law to have multiple wives (unless prohibited by additional government laws), extra-marital relations between a single woman and a married man would not be adultery, and neither person would face prosecution in the theocratic courts; nevertheless, it would be a violation of the prohibition on relations outside marriage (see commandment -355), and would bring punishment from Heaven.