Ruler \Rul"er\ (r[udd]l"[~e]r), 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)

Source: Webster's Revised Unabridged Dictionary (1913)