D.A.youdaoicibaDictYouDict[D.A. 词源字典]
American English initialism (acronym) for district attorney from 1934; for duck's ass haircut (or, as OED would have it, duck's arse), from 1951. The haircut so called for the shape at the back of the head.[D.A. etymology, D.A. origin, 英语词源]
district (n.)youdaoicibaDictYouDict
1610s, "territory under the jurisdiction of a lord or officer," from French district (16c.), from Medieval Latin districtus "restraining of offenders, jurisdiction," then under the feudal system "area of jurisdiction," noun use of past participle of Latin distringere "hinder, detain" (see distress). Used vaguely of "any tract of land" from 1712. District attorney attested by 1789, American English.