cart horse(n = noun.animal) carthorse, drayhorse - draft horse kept for pulling carts;
is a kind of draft horse, draught horse, dray horse

   a horse kept for pulling carts; a horse bred or used for drawing heavy loads. [WordNet 1.5]

N  carrier, porter, bearer, tranter, conveyer, cargador, express, expressman, stevedore, coolie, conductor, locomotive, motor, beast, beast of burden, cattle, horse, nag, palfrey, Arab, blood horse, thoroughbred, galloway, charger, courser, racer, hunter, jument, pony, filly, colt, foal, barb, roan, jade, hack, bidet, pad, cob, tit, punch, roadster, goer, racehorse, pack horse, draft horse, cart horse, dray horse, post horse, ketch, Shetland pony, shelty, sheltie, garran, garron, jennet, genet, bayard, mare, stallion, gelding, bronco, broncho, cayuse, creature, critter, cow pony, mustang, Narraganset, waler, stud, Pegasus, Bucephalus, Rocinante, ass, donkey, jackass, mule, hinny, sumpter horse, sumpter mule, burro, cuddy, ladino, reindeer, camel, dromedary, llama, elephant, carrier pigeon, pallet, brace, cart, dolley, support, fork lift, carriage, ship, equine, asinine.

american saddle horse, cart, cart away, cart load, cart off, cart track, cavalry horse, charley horse, coach horse, crazy horse, dark horse, dawn horse, donkey cart, draft horse, draught horse, dray horse, farm horse, female horse, garden cart, gift horse, golf cart, gymnastic horse, harness horse, high horse, horse, horse around, horse balm, horse barn, horse bean, horse blanket, horse botfly, horse breeding, horse brier, horse cart, horse cassia, horse cavalry, horse chestnut, horse doctor, horse fancier, horse fly, horse gentian, horse grain, horse gram, horse guards, horse latitude, horse latitudes, horse mackerel, horse manure, horse mushroom, horse nettle, horse of the wood, horse opera, horse parsley, horse pistol, horse power, horse race, horse racing, horse radish, horse sense, horse show, horse thistle, horse tick, horse trade, horse trader, horse trading, horse wrangler, iron horse, laundry cart, lawn cart, long horse, male horse, one horse, pack horse, pastry cart, plantation walking horse, plough horse, plow horse, pole horse, pommel horse, pony cart, post horse, przevalski's horse, przewalski's horse, quarter horse, race horse, riding horse, river horse, rocking horse, saddle horse, sea horse, serving cart, shire horse, shopping cart, side horse, stalking horse, stick horse, t cart, tandem cart, tea cart, tennessee walking horse, three-year-old horse, towel horse, trojan horse, trotting horse, two-year-old horse, vaulting horse, walking horse, war horse, water cart, watering cart, wheel horse, white horse, white horse nettle, wild horse, wooden horse