treyf

Treif, treyf, or tref is a term used in Jewish dietary law to denote foods that are not kosher or not fit for consumption according to kashrut. The word comes from Yiddish treyf, itself derived from the Hebrew tref (terefah), meaning torn or unfit. In traditional usage, trefa originally referred to a carcass deemed non-kosher due to injury or illicit slaughtering, but in modern contexts it denotes anything that does not comply with kashrut.

Most commonly, treyf refers to foods from non-kosher animals (such as pork or shellfish), animals forbidden by species, or meat that has not been slaughtered or prepared according to ritual rules. It also includes foods from creatures that lack certain kosher criteria, such as fish without both fins and scales, and birds of prey or scavengers. In addition, treyf can cover products derived from non-kosher ingredients or processed with non-kosher equipment, as well as certain prohibited combinations, such as meat and dairy in the same dish.

In practice, observant Jews follow kashrut to avoid treyf, often seeking kosher certification on products. The term also appears in broader or metaphorical usage to describe anything considered outside traditional Jewish dietary norms or standards.