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1. Make impure in a bad way; make something harmful, especially by the addition of some unwanted substance
   "The industrial wastes contaminated the lake";
   - pollute, foul
    
2. Make radioactive by adding radioactive material
   "Don't drink the water--it's contaminated"

Derived forms: contaminated, contaminates, contaminating

Type of: alter, begrime, bemire [archaic], change, colly [archaic], dirty, grime, modify, soil

Antonym: decontaminate

Encyclopedia: Contaminate