(of food, or premises in which food is sold, cooked, or eaten) satisfying the requirements of Jewish law. (Oxford Dictionaries)
(of food or places where food is sold, etc.) prepared or kept in conditions that follow the rules of Jewish law. (Cambridge Dictionary)
Something, especially food, that is kosher is approved of or allowed by the laws of Judaism. (Collins Dictionary)
Is It Easier To Keep Shabbat Than It Is To Keep Kosher?