Where does “ниць” come from?

ниць (Old East Slavic) comes from Proto-Slavic nĩcь — lying face downwards.

Ancestry of “ниць”, step by step

StepLanguageWordMeaning
1Proto-Slavicnĩcьlying face downwards
Every word from Proto-Slavic nĩcь
ниць — Etymology, Origin & Word History | Etymology Explorer