Synonyms for pollution

Most common

1. Defilement — moral or spiritual corruption; impurity, degradation, defilement

2. Contamination — something that pollutes; a pollutant

3. Sophistication — physical contamination, now especially the contamination of the environment by harmful substances, or by…

4. Adulteration — the desecration of something holy or sacred; defilement, profanation

Other

violation, desecration, befoulment

conservation, antipollution

n. 1
Physical contamination, now especially the contamination of the environment by harmful substances, or by disruptive levels of noise, light etc.
Pollution levels are almost always higher in cities rather than the countryside, what with the cars, industry and so on.
n. 2
Something that pollutes; a pollutant.
n. 3
The desecration of something holy or sacred; defilement, profanation.
n. 4
Moral or spiritual corruption; impurity, degradation, defilement.

Use in printed books, per decade from 1850 to 2019.

5 letters: filth¹, taint¹
7 letters: pravity, soilage
8 letters: impurity⁴, baseness
9 letters: infection³, violation⁴, depravity⁴, pollutant³, obliquity, vitiation
10 letters: corruption³, perversion³, defilement, debasement³, adulterant, defedation, befoulment
11 letters: abomination⁵, desecration⁴, contaminant⁴, profanation⁴, defoedation, debauchment
12 letters: adulteration⁵, sophisticant
13 letters: contamination⁵
14 letters: sophistication⁵

The small number after each word is its number of syllables (impurity⁴ = 4 syllables).