Green’s Dictionary of Slang

1. (US) the generic name for a typical ‘Bowery b’hoy’, a proletarian New Yorker who might work as a fireman but whose main occupation was running with a gang, mixing street thuggery with life as a political mercenary [the name, if not the type, was originated by Edward Judson (1823–86), a political fixer and bullyboy, who wrote a number of blood-and-thunder burlesques featuring Mose, Lize and their friend Sykesy; note also B.A. Baker’s play, A Glance at New York (1848), featuring ‘Mose’, a character based on the real-life Moses ‘Old Mose’ Humphreys, a leader of the Bowery B’hoys, a ferocious street brawler and a fireman of Lady Washington Engine Co. No. 40].

1849		G.G. Foster N.Y. in Slices 44: Many a half-timid young man [...] has been confirmed in vicious courses by witnessing and contributing to the applauses with which the beastly exuberance of ‘Mose’ was received from the stage.
1851		W.K. Northall Curtain 92: Mose, instead of appearing on the stage, was in the pit, the boxes, and the gallery [DA].
1873		J. O’Connor Wanderings of a Vagabond 268: ‘Yaas, Govey, stash it, ole hoss, yer too long-winded,’ drawled a gentleman of the ‘Mose’ order, who was standing immediately opposite Mr. McGovern, and who, to give point to his remark, favored that gentleman with such a punch in the ribs as brought the water to his eyes and sent him reeling to the opposite side of the room.

2. (US black) a black man, esp. one who is subservient to whites [proper name Moses, a stereotypically ‘black’ name].

1928		N.I. White Amer. Negro Folk-Songs 180: [reported from Auburn, Ala., 1915–1916] I’m des a little nigger, / De white folks call me Mose.
1937		Fats Waller ‘The Joint is Jumpin’’ 🎵 Every Mose is on his toes, / I mean this joint is jumpin’!
1944		D. Burley Orig. Hbk of Harlem Jive 76: Negro — Mose.
1966		B. Jackson Get Your Ass in the Water (1974) 207: I got a Irishman for a chauffeur, and they call my butler ‘Mose’.
1972		K. Johnson ‘Vocab. of race’ in Kochman Rappin’ and Stylin’ Out 148: Mose. Derived from the biblical character, Moses, and refers to old black men — especially to those whose behavior is that of the stereotyped rural black.
1980		J.L. Gwaltney Drylongso xvi: Mose – an archetypal representation of the average ‘straight’ black male.