Where does “стеречи” come from?

стеречи (Old East Slavic) comes from Proto-Slavic sterťi, from Proto-Slavic stergti, from Proto-Indo-European sterg- — rigid, stiff; to love.

Ancestry of “стеречи”, step by step

StepLanguageWordMeaning
1Proto-Slavicsterťito guard
2Proto-Slavicstergtito protect, to watch over
3Proto-Indo-Europeansterg-rigid, stiff; to love
Every word from Proto-Indo-European sterg- →Every word from Proto-Slavic stergti →Every word from Proto-Slavic sterťi →
стеречи — Etymology, Origin & Word History | Etymology Explorer