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late 12c., from Old English Hacan ieg "Haca's Isle" (or possibly "Hook Island"), the "isle" element here meaning dry land in a marsh. Now well within London, it once was pastoral and horses apparently were kept there. Hence hackney "small saddle horse let out for hire" (c.1300), with subsequent deterioration of sense (see hack (n.2)). And cf. French haquenée "ambling nag," an English loan-word.
any carriage plying for hire, although hackney coach usually refers to a four-wheeled carriage drawn by two horses and holding six passengers. Hackneys were introduced into England early in the 17th century and may have been named for a section of London. In 1654 there were 300 licensed hackney coaches allowed in London and its environs, and by 1832 there were about 1,200
inner borough of London, in the historic county of Middlesex. Hackney lies north of the City of London and Tower Hamlets, and its eastern boundary is the River Lea. It was created a borough in 1965 by the amalgamation of the former metropolitan boroughs of Shoreditch, Hackney, and Stoke Newington. Hackney includes areas and historic villages such as (from north to south) Stoke Newington, Upper Clapton, Lea Bridge, Lower Clapton, Dalston, Homerton, Hackney Wick, Hackney, Kingsland, Haggerston, Hoxton, and Shoreditch. Shoreditch, near the City, is industrial and commercial in character, whereas the rest of Hackney is largely residential with pockets of industry, notably along the Lea valley.