Green’s Dictionary of Slang

a prostitute.

1641–74		‘North Countrey-Taylor’ in Rawlinson coll. ballads n.p.: One of the City Mobs.
c.1655		‘The Merry Man’s Resolution’ in Ebsworth Bagford Ballads (1878) II 486: Farewel unto Shore-ditch, and More-fields eke also, / Where Mobs to pick up Cullies, a night-walking do go.
1660		‘Peter Aretine’ Strange and True Newes 3: Night-walkers, Mobbs and wandring whores, such as Mrs. Diamond whose nose lies flat.
c.1670		‘Two Penny Whore’ in Euing Broadside Ballads No. 191: A Lusty young Shaver [...] chanced with one of his Mobs for to meet, All in her silks [...] adorned, With Complement he there his Mopsie did greet.
1679		‘Poets Dream’ in Pepys Ballads (1987) IV 302: Your Moore field Mobbs, and Whetston-Whores.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1867		Nat. Police Gaz. (NY) 26 Oct. n.p.: Her den is filled with a crowd of played out ‘mobs,’ whose chief occupation is to steal.