bulldog

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of a breed of short-haired dog characterized by a large head, strong square jaws with dewlaps, and a stocky body. It was originally bred for bullbaiting.
2. n. A short-barreled, large-caliber revolver or pistol.
3. n. A heat-resistant material used to line puddling furnaces.
4. n. Chiefly British A proctor's assistant at Oxford University or Cambridge University.
5. adj. Stubborn.
6. v. Western U.S. To throw (a calf or steer) by seizing its horns and twisting its neck until the animal falls.

Century Dictionary and Cyclopedia

1. n. A variety of dog of comparatively small size, but very strong and muscular, with a large head, broad muzzle, short hair, tapering smooth tail, and remarkable courage and ferocity. Dogs of this kind were formerly much used in bullbaiting, whence the name.
2. n. A bailiff.
3. n. The assistant or servant who attends the proctor of an English university when on duty.
4. n. A pistol; in recent use, a small revolver with a short barrel carrying a large ball.
5. n. Nautical: The great gun in the officers' wardroom cabin.
6. n. A general term for main-deck guns.
7. n. In metallurgy, tap-cinder from the puddling-furnace, after the protoxid of iron has been converted into sesquioxid by roasting. It may be used as an ore of iron for making what is known as cinder-iron. It is also extensively used as a lining for the sides of the puddling-furnace.
8. n. A name given by the Canadian half-breeds to the gadfly.
9. n. Same as bulldog ant.

Wiktionary

1. n. A breed of dog developed in England by the crossing of the bullbaiting dog and the Pug to produce a ladies companion dog. Having a very smooth coat, a flattened face, wrinkly cheeks, powerful front legs and smaller hind legs.
2. n. A shortened form of British bulldog.
3. n. A stubborn person.
4. v. transitive To chase (a steer) on horseback and wrestle it to the ground by twisting its horns (as a rodeo performance).

GNU Webster's 1913

1. n. (Zoöl.) A variety of dog, of remarkable ferocity, courage, and tenacity of grip; -- so named, probably, from being formerly employed in baiting bulls.
2. n. (Metal.) A refractory material used as a furnace lining, obtained by calcining the cinder or slag from the puddling furnace of a rolling mill.
3. adj. Characteristic of, or like, a bulldog; stubborn.

WordNet 3.0

1. v. attack viciously and ferociously
2. n. a sturdy thickset short-haired breed with a large head and strong undershot lower jaw; developed originally in England for bull baiting
3. v. throw a steer by seizing the horns and twisting the neck, as in a rodeo