impurity
definition
the quality or state of being impure or mixed with foreign or unclean substances
example
The scientist conducted tests to determine the level of impurity in the water sample collected from the river.
synonyms
contaminationadulterationpollution
word origin — Middle English 'impurite', from Old French 'impurité', from Latin 'impuritas', from 'in-' (not) + 'purus' (pure)