From Longman Dictionary of Contemporary Englishkosherko‧sher /ˈkəʊʃə $ ˈkoʊʃər/ adjective 1 a) RRJkosher food is prepared according to Jewish law b) DFkosher restaurants or shops sell food prepared in this way2 HONEST informal something that is kosher is honest, legal, or really what it is claimed to be Are you sure this offer is kosher?
Examples from the Corpus
kosher• kosher meats• This deal doesn't sound quite kosher to me.Origin kosher (1800-1900) Yiddish Hebrew kasher “fit, suitable” 