[1] : The Collaborative International Dictionary of English v.0.48

hansom \han"som\ ha^n"su^m, n., hansom cab \han"som cab`\
   ka^b`. from the name of the inventor.
   a light, low, two-wheeled covered carriage with the driver's
   seat elevated behind, the reins being passed over the top.
   1913 webster

         he hailed a cruising hansom . . . " 'tis the gondola of
         london," said lothair.                   --beaconsfield.
   1913 webster

[2] : WordNet (r) 2.0

hansom
     n : a two-wheeled horse-drawn covered carriage with the driver's
         seat above and behind the passengers syn: hansom cab
see also:
hansom cab 

Hansom >> H Words
Hansom, definition of term: Hansom
hansom_pag1.html