Etymology Dictionary

HACKNEY, HACK,  a horse let out for hire.  (F.,—Du.)   M. E. hakeney; Chaucer, C. T. 16027; P. Plowman, B. v. 318.—O. F. haquenée, hacquenée, 'an ambling horse, gelding, or mare;' Cot.   Cf. Span. hacanea, Ital. chinea (short for acchinea), the same.—O. Du. hackeneye, an hackney (Hexham).   β. Of obscure origin; but probably derived from Du. hakken, to hack, chop, hew, mince; and Du. negge, a nag.   Cf. Swed. hacka, to hack, hew, peck, chatter with cold, stammer, stutter; this suggests that the Du. hakken was here familiarly used in the sense of 'jolt;' and, probably, the orig. sense was 'jolting nag,' with reference to the rough horses which customers who hired them had to put up with, or with reference to their 'faltering' pace.   See Hack and Nag.   ¶ Littré gives the syllable hack in this word the sense of 'horse;' this is quite wrong, as hack in the sense of 'horse' is merely a familiar abbreviation of hackney, just as cab stands for cabriolet, or bus for omnibus.   So, too, the verb to hack, in the sense of 'treat roughly,' or 'use for rough riding,' is quite modern, and due to the abbreviated form of the substantive.   Der. hackney-ed, hackney-coach.