1. A thin straight piece or bar of material, such as metal or wood, often having a particular function or use, as:
   1. A fishing rod.
   2. A piston rod.
   3. An often expandable horizontal bar, especially of metal, used to suspend household items such as curtains or towels.
   4. A leveling rod.
   5. A lightning rod.
   6. A divining rod.
   7. A measuring stick.
2. A shoot or stem cut from or growing as part of a woody plant.
3. 1. A stick or bundle of sticks or switches used to give punishment by whipping.
   2. Punishment; correction.
4. A scepter, staff, or wand symbolizing power or authority.
5. Power or dominion, especially of a tyrannical nature: "under the rod of a cruel slavery" (John Henry Newman).
6. (Abbr. rd)
   1. A linear measure equal to 5.5 yards or 16.5 feet (5.03 meters). Also called pole.
   2. The square of this measure, equal to 30.25 square yards or 272.25 square feet (25.30 square meters).
7. Bible. A line of family descent; a branch of a tribe.
8. Anatomy. Any of various rod-shaped cells in the retina that respond to dim light.
9. Microbiology. An elongated bacterium; a bacillus.
10. Slang. A pistol or revolver.
11. A portion of the undercarriage of a train, especially the drawbar under a freight car. Often used in the plural: ride the rods.

[Middle English rodd, from Old English.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.