unarmed (adj.)youdaoicibaDictYouDict[unarmed 词源字典]
c. 1300, "with armor removed," from un- (1) "not" + armed, or else past participle adjective from unarm "strip of armor" (c. 1300), from un- (2) "opposite of" + arm (v.). Meaning "not fitted to attack, weaponless" is from late 14c.[unarmed etymology, unarmed origin, 英语词源]