Where does “нечистоћа” come from?
нечистоћа (Serbo-Croatian) comes from Serbo-Croatian чисто̀ћа, from Serbo-Croatian чи̏ст, from Proto-Slavic čistъ, from Proto-Balto-Slavic skīstas, from Proto-Indo-European skidtos, from Proto-Indo-European (s)keyd-.
нечистоћа (Serbo-Croatian): dirt, filth; impurity
Ancestry of “нечистоћа”, step by step