Etymology

Recorded since c.1340, as "discharge of semen other than during sex," later, "desecration, defilement" (1382), from Late pollutio "defilement," from Latin polluere "to soil, defile, contaminate", itself from por- "before" + -luere "to smear" (related to lutum "mud" and to lues "filth", cfr. Greek (lyma) "filth, dirt, disgrace" and (lymax) "rubbish, refuse," Old Irish loth "mud, dirt," Lithuanian lutynas "pool, puddle"). Sense of "contamination of the environment" first recorded c.1860

Noun

1. The act of polluting or the state of being polluted, especially the contamination of the environment by harmful substances.

   Nobody visits the river any more because of all the pollution.

2. Something that pollutes; a pollutant.
3. Physical defilement