rod

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

• noun A thin straight piece or bar of material, such as metal or wood, often having a particular function or use, as.
• noun A fishing rod.
• noun A piston rod.
• noun An often expandable horizontal bar, especially of metal, used to suspend household items such as curtains or towels.
• noun A leveling rod.
• noun A lightning rod.
• noun A divining rod.
• noun A measuring stick.
• noun One of the horizontal elements in a truss system underneath a rail car, especially a freight car.
• noun A shoot or stem cut from or growing as part of a woody plant.
• noun A stick or bundle of sticks or switches used to give punishment by whipping.
• noun Punishment; correction.
• noun A scepter, staff, or wand symbolizing power or authority.
• noun Power or dominion, especially of a tyrannical nature.
• noun A linear measure equal to 5.5 yards or 16.5 feet (5.03 meters).
• noun The square of this measure, equal to 30.25 square yards or 272.25 square feet (25.30 square meters).
• noun Anatomy Any of various rod-shaped cells in the retina that respond to dim light.
• noun Microbiology An elongated bacterium; a bacillus.
• noun Slang A pistol or revolver.
• noun Vulgar Slang A penis, especially when erect.

from The Century Dictionary.

• To furnish with a rod or rods; specifically, in recent use, to furnish or equip with lightning-rods.
• To operate upon with a rod, in any way.
• noun A Middle English form of road.
• noun A Middle English form of rode, preterit of ride.
• noun The central cone or peg in a gustatory cup on an insect's epipharynx.
• noun Any gorgonian with long, cylindrical branches.
• noun A shoot or slender stem of any woody plant, more especially when cut off and stripped of leaves or twigs; a wand; a straight slender stick; a cane; also, anything of similar form: as, a brass rod.
• noun Specifically— An instrument of punishment or correction; a single switch or stick, or a bundle of switches; hence, chastisement.
• noun The badge of office of certain officials who are in a sense guardians or controllers of others, or ushers, marshals, and the like. The use of rods of certain colors gives names to their bearers: as, in England, black-rod, green-rod, etc. See black-rod.
• noun A scepter; hence, figuratively, authority; sway.
• noun An enchanter's wand, or a wand possessing the power of enchantment.
• noun A long, light, tapering, elastic pole used in angling, to which the line is attached, now usually made in adjustable sections or joints, and fitted with guides and a reel. There are eight woods commonly used for rods, of which four are solid (greenheart, hickory, ash, and willow) and four are hollow (East Indian bamboo, Carolina and West Indian cane, white cane, and jungle-cane). Rods have also been made of hard rubber and of steel. Jointed rods are made in three or four pieces, of which the largest and heaviest is the butt, and the slenderest is the tip. The joints are fitted with metal rings or ferrules, and with small rings called guides to receive the line. The reel is stepped into the butt, near its end, or otherwise suitably attached, as by a reel-plate. The special makes of rods are very numerous, and their names almost equally so. Besides being named and classed according to the material of which they are composed, as bamboo rod, etc., they are commonly identified with the name of the fish for which they are specially designed: as, salmon-rod, trout-rod, bass-rod, etc. All rods are, however, divisible into three classes, according to their make and purpose. These are the fly-rod, which is long, slender, tapering, tough, and highly elastic; the trolling-rod, which is comparatively short, stout, and stiff; and the bait-rod, which is a mean between the other two. Fly-rods are most used, with artificial flies. Split-bamboo rods are now manufactured for all kinds of angling. See fly-rod, and cut under reel.
• noun An instrument for measuring.
• noun In mech., any bar slender in proportion to its length, particularly such a bar used as a brace or a tie between parts for connecting them, or for strengthening a connection between them.
• noun Specifically, in a steam-engine, the pitman which connects the cross-head with the crank: also and more generally called connecting-rod. The connection is made at the cross-head to the cross-head pin, and at the crank to the crank-wrist. See cut under steam-engine.
• noun A measure of length equal to 5½ yards, or 16½ feet. (Also called pole and perch.) A square rod is the usual measure of brickwork, and is equal to 272¼ square feet.
• noun A shoot or branch of a family; a tribe or race.
• noun In anatomy, one of numerous slender rod-like or bacillary structures which collectively form, together with similar but conical bodies called cones, one of the layers of which the retina of the eye is composed, called the layer of rods and cones, essential to the function of vision. See cut under retina.
• noun In entomology, specifically, any differentiation of the anterior end of a retinal cell of the eye, which may unite to form a rhabdom. See rhabdomere.
• noun A fishing-rod made in sections of split bamboo strips.

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

• noun A straight and slender stick; a wand; hence, any slender bar, as of wood or metal (applied to various purposes).
• noun An instrument of punishment or correction; figuratively, chastisement.
• noun A kind of sceptor, or badge of office; hence, figuratively, power; authority; tyranny; oppression.
• noun A support for a fishing line; a fish pole.
• noun (Mach. & Structure) A member used in tension, as for sustaining a suspended weight, or in tension and compression, as for transmitting reciprocating motion, etc.; a connecting bar.
• noun An instrument for measuring.
• noun A measure of length containing sixteen and a half feet; -- called also perch, and pole.