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

using speech rather than writing; an oral tradition; an oral agreement

[ Syn: oral ]

said or done without having been planned or written in advance; he made a few ad-lib remarks

[ Syn: ad-lib , spontaneous ]