contaminating (Adjective) — Spreading pollution or contamination; especially radioactive contamination.
contaminating (Adjective) — That infects or taints.
contaminating (Verb) — Make impure in a bad way; make something harmful, especially by the addition of some unwanted substance. ex. "The industrial wastes contaminated the lake"
contaminating (Verb) — Make radioactive by adding radioactive material. ex. "Don't drink the water--it's contaminated"