Rod \Rod\, n. [The same word as rood. See Rood.]

1. A straight and slender stick; a wand; hence, any slender bar, as of wood or metal (applied to various purposes). Specifically:
   (a) An instrument of punishment or correction; figuratively, chastisement.

He that spareth his rod hateth his son. --Prov. xiii. 24.
   (b) A kind of sceptor, or badge of office; hence, figuratively, power; authority; tyranny; oppression. ``The rod, and bird of peace.'' --Shak.
   (c) A support for a fishing line; a fish pole. --Gay.
   (d) (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.
   (e) An instrument for measuring.

2. A measure of length containing sixteen and a half feet; -- called also perch, and pole.

Black rod. See in the Vocabulary.

Rods and cones (Anat.), the elongated cells or elements of the sensory layer of the retina, some of which are cylindrical, others somewhat conical.

Source: Webster's Revised Unabridged Dictionary (1913)