Pollution (noun)

1. The presence or introduction into the environment of a substance or thing that has harmful or poisonous effects.
2. The action or process of polluting or the state of being polluted.

Origin:

Late middle english: from latin pollutio(n-), from polluere "to defile".

Examples:

1. Air pollution is a major problem in the city.
2. The factory was closed due to water pollution.
3. The pollution of the river made it unsafe to swim.
4. The government is taking steps to reduce pollution.
5. The noise pollution in the city is causing health problems for residents.