1. superlative form of impure; containing the most unwanted or foreign substances; least pure
Usage: superlative degree
2. superlative form of impure; morally or ethically the most corrupt or unclean
Usage: superlative degree; figurative

Examples

• The impurest water samples showed the highest levels of bacterial contamination.
• Of all the metals tested, this alloy was the impurest due to excessive iron content.
• His motives were impurest, driven entirely by greed and self-interest.
• The impurest form of the chemical compound contained multiple unwanted byproducts.
• She accused him of having the impurest intentions toward her family.
• The impurest air quality was recorded in the industrial district.