wallah (n.)youdaoicibaDictYouDict[wallah 词源字典]
also walla, "person employed (in some specified business)," Anglo-Indian, from Hindi -wala, suffix forming adjectives with the sense "pertaining to, connected with;" the functional equivalent of English -er (1). Europeans took it to mean "man, fellow" and began using it as a word.[wallah etymology, wallah origin, 英语词源]