Ruler /(rṳl"ẽr)/

Rul·er

Ruler

n.
  1. One who rules; one who exercises sway or authority; a governor.
    And he made him ruler over all the land.
    — Gen. xli. 43.
    A prince and ruler of the land.
  2. A straight or curved strip of wood, metal, etc., with a smooth edge, used for guiding a pen or pencil in drawing lines. Cf. Rule, n., 7 (a)<-- usu. marked with graduations so that it can be used to measure distances -->.

Phrases & Compounds

Parallel ruler
See under Parallel.