mid-14c., "not prepared," from un- (1) "not" + ready (adj.).
In English history, applied from c. 1200 (Etheldredus Unrad) to Anglo-Saxon King Æðelræd II (968-1016), where it preserves Middle English unredi, a different adjective, from Old English ungeræd "ill-advised, rede-less, no-counsel" and plays on the king's name (which means "good-counsel"). Old English ræd "advice, counsel" is related to read (v.). Rede "counsel" survived in poetic usage to 17c. An attempted revival by Scott (19c.) failed, though it is used in Tolkien's "Lord of the Rings."