Literally, the word refers to something disgusting, abhorrent, wicked. The word is used to describe acts of homosexuality or bestiality (Leviticus 18:22–23), or taking to oneself the images of heathen gods (Deuteronomy 7:25), or eating unclean foods (Deuteronomy 14:3), or engaging in pagan practices such as child-sacrifice, divination and magic (Deuteronomy 18:9–12). In effect, Malachi charges the people of God with conducting themselves as the pagans, a most serious charge for a people set apart as “holy to the Lord” (Deuteronomy 7:6, Deuteronomy 26:18).
11 Judah has been faithless, and abomination has been committed in Israel and in Jerusalem. For Judah has profaned the sanctuary of the LORD, which he loves, and has married the daughter of a foreign god.