POLLUTION

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

From the International Standard Bible Encyclopedia
Edited by James Orr, published in 1939 by Wm. B. Eerdmans Publishing Co.