Polack (n.)youdaoicibaDictYouDict[Polack 词源字典]
"Polish person," 1570s, from Polish Polak "(male) Polish person," related to Polanie "Poles," Polska "Poland," polski "Polish" (see Pole). In North American usage, "Polish immigrant, person of Polish descent" (1879) and in that context considered offensive in English. As an adjective from c. 1600.[Polack etymology, Polack origin, 英语词源]