The Collaborative International Dictionary of English v.0.48:

Cart \Cart\ (k[aum]rt), n. [AS. cr[ae]t; cf. W. cart, Ir. &
   Gael. cairt, or Icel. kartr. Cf. Car.]
   1. A common name for various kinds of vehicles, as a Scythian
      dwelling on wheels, or a chariot. "Ph[oe]bus' cart."
      --Shak.
      [1913 Webster]

   2. A two-wheeled vehicle for the ordinary purposes of
      husbandry, or for transporting bulky and heavy articles.
      [1913 Webster]

            Packing all his goods in one poor cart. --Dryden.
      [1913 Webster]

   3. A light business wagon used by bakers, grocerymen,
      butchers, etc.
      [1913 Webster]

   4. An open two-wheeled pleasure carriage.
      [1913 Webster]

   Cart horse, a horse which draws a cart; a horse bred or
      used for drawing heavy loads; -- also spelled carthorse.


   Cart rope, a stout rope for fastening a load on a cart; any
      strong rope.

   To put the cart before the horse, To get the cart before
   the horse, or To set the cart before the horse, to invert
      the order of related facts or ideas, as by putting an
      effect for a cause; to do things in an improper order.
      [1913 Webster +PJC]

The Collaborative International Dictionary of English v.0.48:

carthorse \cart"horse`\, cart horse \cart" horse`\n.
   a horse kept for pulling carts; a horse bred or used for
   drawing heavy loads.

   Syn: drayhorse.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

carthorse
    n 1: draft horse kept for pulling carts [syn: carthorse, cart
         horse, drayhorse]