to render (something) impure or unfit for use through contact with or the admixture of a polluting or poisonous substance
to make (something) radioactive through exposure to a radioactive substance
to destroy the purity and innocence of (somebody or something) through unwholesome or undesirable influences
contaminant noun
contamination /-ʹnaysh(ə)n/ noun
contaminative /-nətiv/ adj
contaminator noun
[Latin contaminatus, past part. of contaminare, from contamen contact, defilement, from con- + a word related to tangere to touch]