1 dirty, soiled, unclean, sullied, tainted, polluted, defiled, foul, filthy, feculent, infected, scummy, putrid, putrescent, rotten:
The water is impure and not fit to drink.
2 mixed, alloyed, contaminated, adulterated, debased, unrefined:
Impure ore contains other substances which are removed during processing
3 unclean, unhallowed, forbidden, disallowed, Judaism tref or treif or treifa:
Certain foods are considered impure in some religions.
4 unchaste, immoral, sinful, wicked, evil, vile, unvirtuous, unvirginal, corrupted, defiled, debased, vitiated, degenerate, depraved, loose, wanton, lustful, promiscuous, libidinous, dissolute, licentious, obscene, prurient, dirty, filthy, lubricious or lubricous, salacious, lascivious, lewd, lecherous:
The book was condemned as 'likely to encourage impure thoughts'.