To make unfit for or harmful to living things, especially by the addition of waste matter. See Synonyms at contaminate. To make less suitable for an activity, especially by the introduction of unwanted factors: The stadium lights polluted the sky around the observatory. To render impure or morally harmful; corrupt. To make ceremonially impure; profane: "Churches and altars were polluted by atrocious murders\u201d ( Edward Gibbon).