contaminate

Short definition from Wiktionary

Verb

1. 1
   To make something dangerous or toxic by introducing impurities or foreign matter.
2. 2
   To soil, stain, corrupt, or infect by contact or association.
3. 3
   To make unfit for use by the introduction of unwholesome or undesirable elements.
4. 4
   To infect, usually of a deadly virus.

Adjective

1. 1
   Contaminated.
2. 2
   Dirty, sinful, wicked, gross, etc.