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 body of evidence that constitute the offence; the objective proof that a crime has been committed (sometimes mistakenly thought to refer to the body of a homicide victim)
(biology) the field of science concerned with processes of communication and control (especially the comparison of these processes in biological and artificial systems)