Merriam-Webster Collegiate Dictionary - horse

 I. noun  (plural ~s; also ~)  Etymology: Middle English hors, from Old English; akin to Old High German hros ~  Date: before 12th century  1.  a.  (1) a large solid-hoofed herbivorous ungulate mammal (Equus caballus, family Equidae, the ~ family) domesticated since prehistoric times and used as a beast of burden, a draft animal, or for riding  (2) race~ play the ~s  b. a male ~; especially stallion  c. a recent or extinct animal (as a zebra, ass, or onager) of the ~ family  2.  a. jackstay  b. a frame usually with legs used for supporting something (as planks or staging)  c.  (1) pommel ~  (2) vaulting ~  3. ~ plural cavalry  4. a mass of the same geological character as the wall rock occurring within a vein  5. ~power  6. slang heroin  7. an athlete whose performance is consistently strong and reliable a team with the ~s to win the pennant  8. or H-O-R-S-E a game in which players take turns attempting to duplicate successful basketball shots, a letter of the word "~" is awarded for each missed attempt, and the first player to receive all five letters loses  • ~less adjective  • ~like adjective  II. verb  (~d; horsing)  Date: before 12th century  transitive verb  1. to provide with a ~  2. to move by brute force  intransitive verb of a mare to be in heat  III. adjective  Date: 15th century  1.  a. of or relating to a ~  b. hauled or powered by a ~ a ~ barge  2. large or coarse of its kind  3. mounted on ~s ~ guards