boss

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

• noun An employer or supervisor.
• noun One who makes decisions or exercises authority.
• noun A professional politician who controls a party or a political machine.
• transitive verb To give orders to, especially in an arrogant or domineering manner.
• adjective First-rate; topnotch.
• noun A cow or calf.
• noun A circular protuberance or knoblike swelling, as on the horns of certain animals.
• noun A raised area used as ornamentation.
• noun Architecture A raised ornament, such as one at the intersection of the ribs in a vaulted roof.
• noun An enlarged part of a shaft to which another shaft is coupled or to which a wheel or gear is keyed.
• noun A hub, especially of a propeller.
• transitive verb To emboss.

from The Century Dictionary.

• noun A cask, especially a small cask; a leather bottle for wine.
• noun A wooden vessel used by plasterers for holding mortar, hung by a hook on a ladder or a wall.
• noun A hassock; a bass.
• To be master of or over; manage; direct; control: as, to boss the house.
• noun The worked-out portion of a mine; the goaf.
• To ornament with bosses; bestud.
• Same as emboss.
• In ceramics, to bring (a surface of boiled oil) to perfect uniformity. See bossing, 1.
• noun A master. Specifically—
• noun In United States politics, an influential politician who uses the machinery of a party for private ends, or for the advantage of a ring or clique; a professional politician having paramount local influence.
• noun The chief; the master; the champion; the best or leading person or thing.
• Chief; master; hence, first-rate: as, a boss mason; a boss player.
• noun A protuberant part; a round, swelling process or excrescence on the body or upon some organ of an animal or plant.
• noun A hump or hunch on the back; a humpback.
• noun A bulky animal.
• noun A fat woman.
• noun A stud or knob.
• noun In sculpture, a projecting mass to be afterward cut or carved.
• noun In architecture, an ornament placed at the intersection of the ribs or groins in vaulted or flat roofs, sometimes richly sculptured with armorial bearings or other devices; also, any projecting ball or knot of foliage, etc., wherever placed.
• noun In mech.: The enlarged part of a shaft on which a wheel is to be keyed, or any enlarged part of the diameter, as the end of a separate piece in a line of shafts connected by couplings. Hollow shafts through which others pass are sometimes also called bosses, but improperly.
• noun A swage or die used for shaping metals.
• noun In ordnance: A cast-iron plate fastened to the back of a traveling-forge hearth.
• noun Any protuberance or lug upon a piece of ordnance.
• noun A soft leather cushion or pad used for bossing (which see), and also for cleaning gilded surfaces and the like in porcelain- and glass-manufacture.
• noun A water-conduit in the form of a tun-bellied figure; a head or reservoir of water.
• noun In geology, an irregular knob-like outcrop of eruptive rock, especially of granite.
• Hollow; empty: as, “his thick boss head,”
• noun In the United States: A familiar name for a cow, or any of the bovine genus: chiefly used in calling or in soothing. On the Western plains, a name for the bison or so-called buffalo.
• In mining, to hole or undercut.

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

• transitive verb To ornament with bosses; to stud.
• noun Slang, U. S. A master workman or superintendent; a director or manager; a political dictator.
• noun Any protuberant part; a round, swelling part or body; a knoblike process.
• noun A protuberant ornament on any work, either of different material from that of the work or of the same, as upon a buckler or bridle; a stud; a knob; the central projection of a shield. See Umbilicus.
• noun (Arch.) A projecting ornament placed at the intersection of the ribs of ceilings, whether vaulted or flat, and in other situations.
• noun A wooden vessel for the mortar used in tiling or masonry, hung by a hook from the laths, or from the rounds of a ladder.