Rul″er (rṳl″ẽr), 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. Shak.
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).
Parallel ruler. See under Parallel.