Source : Webster's Revised Unabridged Dictionary (1913)

Hackney \Hack"ney\, n.; pl. {Hackneys}. [OE. haceney, hacenay;
   cf. F. haquen['e]e a pacing horse, an ambling nag, OF. also
   haquen['e]e, Sp. hacanea, OSp. facanea, D. hakkenei, also OF.
   haque horse, Sp. haca, OSp. faca; perh akin to E. hack to
   cut, and orig. meaning, a jolting horse. Cf. {Hack} a horse,
   {Nag}.]
   1. A horse for riding or driving; a nag; a pony. --Chaucer.

   2. A horse or pony kept for hire.

   3. A carriage kept for hire; a hack; a hackney coach.

   4. A hired drudge; a hireling; a prostitute.

Hackney \Hack"ney\, a.
   Let out for hire; devoted to common use; hence, much used;
   trite; mean; as, hackney coaches; hackney authors. ``Hackney
   tongue.'' --Roscommon.

Hackney \Hack"ney\, v. t. [imp. & p. p. {Hackneyed}; p. pr. &
   vb. n. {Hackneying}.]
   1. To devote to common or frequent use, as a horse or
      carriage; to wear out in common service; to make trite or
      commonplace; as, a hackneyed metaphor or quotation.

            Had I lavish of my presence been, So
            common-hackneyed in the eyes of men.  --Shak.

   2. To carry in a hackney coach. --Cowper.

Source : WordNet®

hackney
     n 1: a carriage for hire [syn: {hackney carriage}, {hackney coach}]
     2: a compact breed of harness horse