discovered or determined by scientific observation; "variation in the ascertained flux depends on a number of factors"; "the discovered behavior norms"; "discovered differences in achievement"; "no explanation for the observed phenomena"
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
such that comparison is impossible; unsuitable for comparison or lacking features that can be compared; "an incomparable week of rest and pleasure"; "the computer proceeds with its incomparable logic and efficiency"; "this report is incomparable with the earlier ones because of different breakdowns of the data"