simple past tense and past participle of contaminate
"The factory was fined after it contaminated the local river with toxic waste last week."
In plain English: To contaminate something means to make it dirty by adding harmful substances to it.
"The workers accidentally contaminated the food supply with dirt from their shoes."
rendered unwholesome by contaminants and pollution
"had to boil the contaminated water"
"polluted lakes and streams"
adulterated; impure
"The milk was found to be contaminated after someone added water to dilute it before selling."