adj 1. very good, excellent, new; COOL, FRESH. Scott Glener of Tucson, AZ, USA suggests the following origin: Kosher is the law of dietary restrictions of Judaism. As Jewish immigrants came to America and ate outside the house more often, they often asked, "Is it Kosher?" The original meaning was, "Am I allowed to eat it?" However, when non-Jewish people heard it, they interpreted the meaning to be "Is it good?" Submitted by Hal Waldron, Chicago, IL, USA, 5-6-1997.
KOSHER
Meaning of KOSHER in English
Slang English vocab. Английский сленговый словарь. 2012