Learner's definition of CONTAMINATE
to make (something) dangerous, dirty, or impure by adding something harmful or undesirable to it
The water was contaminated [=polluted] with chemicals.
Be careful not to allow bacteria to contaminate the wound.
Don't touch the microchip or the oil on your hands will contaminate it.
Make sure the white paint is not contaminated by any of the other colors.
— often used figuratively
[more contaminated; most contaminated]