Green’s Dictionary of Slang

pertaining to prostitution; as v., to work as a prostitute.

1622		Massinger Virgin-Martyr II iii: I know women sell themselves daily, and are hackneyed out for silver.
1734		C. Johnson Hist. of Highwaymen &c. 67: There was not a day hardly past, but I was coached; but at length I hackney’d so long, that I got an ambling Nag: Being recovered, I scorn’d to be dismay’d for one hard bargain; but returned at it again and again.
1748–49		Cleland Memoirs of a Woman of Pleasure (1985) 12: Phoebe herself, that hackney’d, thorough-bred Phoebe, to whom all modes and devices of pleasure were known.
1765		Harris’s List of Covent Garden Ladies 24: She is of a very amorous disposition, has not been much hackneyed [etc] [ibid.] 118: [N]o woman was ever more hackneyed, having been in constant use ever since her thirteenth year.
1790		M.P. Andrews Better Late than Never 43: [of a woman] Hackney’d as the pave—notorious, common — .
1828		G. Smeeton Doings in London 92: By the hackneyed one, I mean those nauseating creatures that ply at the corner of streets.