Pollution

po-lu'-shun (ga'al, "to pollute"; alisgema, "contamination"): In Mal 1:7, "Ye offer polluted bread," i.e. not actually unclean, but worthless, common (compare Ezr 2:62), bread here being used metonymically for sacrificial offerings generally (compare Le 21:6; Mt 6:11). The phrase in Ac 15:20, "the pollutions of idols," is explained in Ac 15:29 by "things sacrificed (the King James Version "meats offered") to idols."

⇒See the definition of pollution in the KJV Dictionary