Where does “отсидка” come from?
отсидка (Russian) comes from Russian отсиде́ть, from Russian сиде́ть, from Old East Slavic сидѣти, from Proto-Slavic sěděti, from Proto-Balto-Slavic *sēdḗˀtei, from Proto-Indo-European sḗd-.
отсидка (Russian): stint
Ancestry of “отсидка”, step by step