(1):
(a.) Ceremonially clean, according to Jewish law; - applied to food, esp. to meat of animals slaughtered according to the requirements of Jewish law. Opposed to tref. Hence, designating a shop, store, house, etc., where such food is sold or used.
(2):
(n.) Kosher food; also, a kosher shop.
(3):
(v. t.) To prepare in conformity with the requirements of the Jewish law, as meat.