
Contaminate
Physical Presence
Contamination often requires direct contact with the harmful substance.
The sterile bandage was contaminated by dirty hands.
Not Always Visible
Impurities from contamination might not be visible to the naked eye.
The water looked clean, but was contaminated with bacteria.
Negative Implication
'Contaminate' implies harm or degradation, not just change.
The pranksters contaminated the town's fountain with dye.