noun

• Physical contamination, now especially the contamination of the environment by harmful substances, or by disruptive levels of noise, light etc.
• Something that pollutes; a pollutant.
• (now rare) The desecration of something holy or sacred; defilement, profanation.
• (now archaic) The ejaculation of semen outside of sexual intercourse, especially a nocturnal emission.
• Moral or spiritual corruption; impurity, degradation, defilement.