horse

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A large hoofed mammal (Equus caballus) having a short coat, a long mane, and a long tail, domesticated since ancient times and used for riding and for drawing or carrying loads.
• noun An adult male horse; a stallion.
• noun Any of various equine mammals, such as the wild Asian species Przewalski's horse or certain extinct forms related ancestrally to the modern horse.
• noun A frame or device, usually with four legs, used for supporting or holding.
• noun Sports A vaulting horse.
• noun Slang Heroin.
• noun Horsepower.
• noun Mounted soldiers; cavalry.
• noun A block of rock interrupting a vein and containing no minerals.
• noun A large block of displaced rock that is caught along a fault.
• intransitive verb To provide with a horse.
• intransitive verb To haul or hoist energetically.
• intransitive verb To be in heat. Used of a mare.
• adjective Of or relating to a horse.
• adjective Mounted on horses.
• adjective Drawn or operated by a horse.
• adjective Larger or cruder than others in the same category.
• idiom (a horse of another/a different) Another matter entirely; something else.
• idiom (beat/flog) To continue to pursue a cause that has no hope of success.
• idiom (beat/flog) To dwell tiresomely on a matter that has already been decided.
• idiom (be/get) To be or become disdainful, superior, or conceited.
• idiom (hold (one's) horses) To restrain oneself.
• idiom (the horse's mouth) A source of information regarded as original or unimpeachable.

from The Century Dictionary.

• An obsolete form of hoarse.
• noun A solidungulate perissodactyl mammal of the family Equidœ and genus Equus; E. caballus.
• noun plural In zoology, the horse family, or Equidæ; the species of the genus Equus and related genera.
• noun The male of the horse kind, in distinction from the female or mare; a stallion or gelding.
• noun A body of troops serving on horseback: cavalry: in this sense a collective noun, used also as a plural: as, a regiment of horse.
• noun A frame, block, board, or the like, on which something is mounted or supported, or the use of which is in any way analogous to that of a horse. Compare etymology of easel.
• noun Specifically— A vaulting-block in a gymnasium.
• noun A wooden frame on which soldiers are made to ride as a punishment: sometimes called a timber mare.
• noun A saw-horse.
• noun A clothes-horse.
• noun A currier’ board, used in dressing hides.
• noun In printing, a sloping board, with its support, placed on the bank close to the tympan of a hand-press, on which is laid the paper to be printed.
• noun A support for the cables of a suspension-bridge.
• noun A board on which the workman sits in grinding the bevels and edges of tools in their manufacture. Also horsing.
• noun In mining, a mass of rock inclosed within a lode or vein, usually of the same material as the “country,” or rock adjacent to the lode on each side.
• noun In metallurgy, same as bear, 7.
• noun An implement or a device for some service suggesting or supposed to suggest that of a horse.
• noun Nautical: A foot-rope.
• noun A jack-stay, on the forward or after side of a mast, on which a sail or yard is hoisted.
• noun A traveler for the sheet-block of a fore-and-aft sail, consisting of a horizontal bar of wood or iron.
• noun The iron bar between the posts of a fife-rail to which the leading-blocks are fastened.
• noun A translation or similar forbidden aid used by a pupil in the preparation of his lessons; a “pony”; a “trot”; a “crib”: so called as helping the pupil to get on faster.
• noun Among British workmen, work charged for before it is executed.
• noun A term of opprobrium. Compare ass, similarly used.