Ruler

Part of speech: noun (n.)

1. One who rules; one who exercises sway or authority; a governor. And he made him ruler over all the land. Gen. xii. 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.