saddle

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

• noun A leather seat for a rider, secured on an animal's back by a girth.
• noun Similar tack used for attaching a pack to an animal.
• noun The padded part of a driving harness fitting over a horse's back.
• noun The seat of a bicycle, motorcycle, or similar vehicle.
• noun Something shaped like a saddle.
• noun A cut of meat consisting of part of the backbone and both loins.
• noun The lower part of a male fowl's back.
• noun A saddle-shaped depression in the ridge of a hill.
• noun A ridge between two peaks.
• intransitive verb To put a saddle onto.
• intransitive verb To load or burden; encumber.
• intransitive verb To saddle a horse.
• intransitive verb To get into a saddle; mount a horse. Often used with up.
• idiom (in the saddle) Prevailing or in control; dominant.
• idiom (in the saddle) Engaged in an activity, especially a job.

from The Century Dictionary.

• To put a saddle upon: as, to saddle a horse.
• To load; encumber as with a burden; also, to impose as a burden.
• noun A contrivance secured on the back of a horse or other animal, to serve as a seat for a rider or for supporting goods packed for transportation.
• noun A part of the harness used for drawing a vehicle. It is a narrow padded cushion laid across the back, and girded under the belly, and is usually held in place by a strap which passes under and around the tail: the shafts or thills are supported by it, the reins pass through rings attached to it, and the check-rein or bearing-rein is hooked to it.
• noun A pack-saddle. See cuts under harness and pad-tree.
• noun A seat prepared for a rider otherwise than on the back of an animal, but resembling an ordinary riding-saddle in design and use, as the seat on a bicycle.
• noun Something resembling a saddle, or part of a saddle, in shape or use.
• noun Nautical, a contrivance of wood notched or hollowed out and used to support a spar, as a wooden saddle-crutch is sometimes used to support the weight of the spanker-boom.
• noun In machinery, a block with a hollowed top to sustain a round object, as a rod, upon a bench or bed.
• noun A block, usually of cast-iron, at the top of a pier of a suspension-bridge, over which pass the suspension-cables or -chains which support the bridge platform. The saddle rests upon rollers, beneath which is a bed bearing upon the top of the pier. The rollers permit a slight movement that compensates for the contractions and expansions of the cables under varying temperatures, which, if the saddle were rigidly secured to the pier, would tend to lessen its stability.
• noun In railroading, the bearing in the axle-box of a carriage; also, a chair or seat for the rails. See cut under axle-box.
• noun In building, a thin board placed on the floor in the opening of a doorway, the width of the jambs.
• noun In zoology and anatomy, some part or configuration of parts like or likened to a saddle. Specifically— The cingulum or clitellum of a worm. A peculiar mark on or modification of the carapace of some crustaceans. See ephippium. The color-mark on the back of the male harp-seal, Phoca (Pagophilus) grœnlandica. Of mutton, veal, or venison, a butchers' cut including a part of the backbone with the ribs on one side. In cephalopods, one of the elevations or saliencies of the sutures of a tetrabranchiate, separated from another by an intervening depression or reentrance called a lobe. In poultry, the rump, or lower part of the back, which in the cock is covered with long linear hackles technically called saddle-feathers, which droop on each side of the root of the tail; also, these feathers collectively. See saddle-feathers.
• noun In botany, in the leaves of Isoetes, a ridge separating the fovea and foveola.
• noun A notched support into the recesses or notches of which a gun is laid to hold it steadily in drilling the vent or bouching.
• noun In gun-making, the base of the foresight of a gun, which is soldered or brazed to the barrel.

from the GNU version of the Collaborative International Dictionary of English.

• noun A seat for a rider, -- usually made of leather, padded to span comfortably a horse's back, furnished with stirrups for the rider's feet to rest in, and fastened in place with a girth; also, a seat for the rider on a bicycle or tricycle.
• noun A padded part of a harness which is worn on a horse's back, being fastened in place with a girth. It serves various purposes, as to keep the breeching in place, carry guides for the reins, etc.
• noun A piece of meat containing a part of the backbone of an animal with the ribs on each side
• noun (Naut.) A block of wood, usually fastened to some spar, and shaped to receive the end of another spar.
• noun (Mach.) A part, as a flange, which is hollowed out to fit upon a convex surface and serve as a means of attachment or support.
• noun (Zoöl.) The clitellus of an earthworm.
• noun (Arch.) The threshold of a door, when a separate piece from the floor or landing; -- so called because it spans and covers the joint between two floors.
• noun (Phys. Geog.) A ridge connected two higher elevations; a low point in the crest line of a ridge; a col.
• noun (Mining) A formation of gold-bearing quartz occurring along the crest of an anticlinal fold, esp. in Australia.
• noun (Arch.) one the small iron bars to which the lead panels of a glazed window are secured.
• noun (Far.) a sore or gall upon a horse's back, made by the saddle.
• noun a band passing round the body of a horse to hold the saddle in its place.
• noun a horse suitable or trained for riding with a saddle.
• noun in sheet-metal roofing, a joint formed by bending up the edge of a sheet and folding it downward over the turned-up edge of the next sheet.