pollution (n.)

mid-14c., pollucioun, "discharge of semen other than during sex," later, "desecration, profanation, defilement, legal or ceremonial uncleanness" (late 14c.), from Late Latin pollutionem (nominative pollutio) "defilement," noun of action from past-participle stem of Latin polluere "to soil, defile, contaminate," probably from *por- "before" (a variation of pro "before, for;" see pro-) + -luere "smear," from PIE root *leu- "dirt; make dirty" (see lutose). Sense of "contamination of the environment" is recorded from c. 1860, but not common until c. 1955.