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1. Undesirable state of the natural environment being contaminated with harmful substances as a consequence of human activities
    
2. The state of being polluted
   - befoulment, defilement
    
3. The act of contaminating or polluting; including (either intentionally or accidentally) unwanted substances or factors
   - contamination
    
4. Waste matter that contaminates the water, air or soil
   - pollutant

Derived forms: pollutions

Type of: dirtiness, dirtying, environmental condition, impureness, impurity, soiling, soilure [archaic], uncleanness, waste, waste material, waste matter, waste product

Encyclopedia: Pollution