imperscriptable (adj.)youdaoicibaDictYouDict[imperscriptable 词源字典]
"unrecorded, without written authority," 1832, used only with right. From assimilated form of Latin in- "not, opposite of" (see in- (1)) + perscribere "to write down."[imperscriptable etymology, imperscriptable origin, 英语词源]