Treif (טרײף) — also trayf, treyf, or tref — is the Yiddish word for food that does not conform with the Jewish dietary laws of kashrut. The word is derived from the Hebrew טְרֵפָה (trēfáh) meaning "torn," and designated foods that are either inherently forbidden or rendered unacceptable due to an incorrect preparation.
Originally, treif designated one category of non-kosher meat: meat from an animal that has been ravaged in the field (terefah), in keeping with prohibition in Exodus 22:30. It was later interpreted to mean any animal or fowl that is unfit for consumption due to a defect, disease or inflicted wound. By extension, the term now applies to all products that are non-kosher.
A kosher animal can be treif if improperly slaughtered or found to be diseased or malformed after inspection by a kashrut supervisor.