phylacter.

Borrowed from French phylactère, from Middle French filatiere, philaterie, philatiere, and Old French filatiere, philatiere (“amulet; reliquary; tefilla”), from Late Latin phylacterium (“amulet; reliquary; tefilla”), from Koine Greek φῠλᾰκτήρῐον (phŭlăktḗrĭon, “amulet; tefilla”) (used in the New Testament to translate Hebrew תפילין (“tefillin”)), from Ancient Greek φῠλᾰκτήρῐον (phŭlăktḗrĭon, “fortified outpost, watchman’s post; protection, safeguard”), from φυλακτήρ (phulaktḗr, “guard, watcher”) + -ῐον (-ĭon, suffix forming nouns). Φυλακτήρ (Phulaktḗr) is derived from φυλακ- (phulak-) (the stem of φῠλᾰ́σσω (phŭlắssō, “to guard, watch; to defend, protect”)) + -τήρ (-tḗr, suffix forming masculine agent nouns); and φῠλᾰ́σσω (phŭlắssō) from φῠ́λᾰξ (phŭ́lăx, “guard, sentry”), probably Pre-Greek.