completely neat and clean; "the apartment was immaculate"; "in her immaculate white uniform"; "a spick-and-span kitchen"; "their spic red-visored caps"
based on custom rather than documentation; "an unwritten law"; "rites...so ancient that they well might have had their unwritten origins in Aurignacian times"- J.L.T.C.Spence
the collection of ancient rabbinic writings on Jewish law and tradition (the Mishna and the Gemara) that constitute the basis of religious authority in Orthodox Judaism