nečistoća

1. (of dirt, dust) dirt; filth
   U podrumu je bilo puno nečistoće i prašine. — The basement was full of dirt and dust.
2. (of a substance) impurity
   Filter uklanja nečistoće iz vode. — The filter removes impurities from the water.
   Ovaj gel čisti nečistoće iz pora. — This gel cleans impurities out of the pores.

In the second sense it is usually plural: nečistoće.