Contamination \Con*tam`i*na"tion\ (k[o^]n*t[a^]m`[i^]*n[=a]"sh[u^]n), n. [L. contaminatio.]

The act or process of contaminating; pollution; defilement; taint; also, that which contaminates.

Source: Webster's Revised Unabridged Dictionary (1913)