Where does “заложник” come from?
заложник (Russian) comes from Russian заложи́ть, from Russian ложи́ть, from Old East Slavic ложити, from Proto-Slavic ložiti, from Proto-Balto-Slavic lágīˀtei, from Proto-Indo-European logʰ-éye-ti, from Proto-Indo-European legʰ- — to lie.
заложник (Russian): hostage
Ancestry of “заложник”, step by step