from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun One, such as a monarch or dictator, that rules or governs.
  • noun A straightedged strip, as of wood or metal, for drawing straight lines and measuring lengths.

from The Century Dictionary.

  • noun One who rules or governs; one who exercises dominion or controlling power over others; a person who commands, manages, restrains, or has part in the making or administration of law; one in authority.
  • noun A rule; an instrument made of wood, brass, ivory, or the like, with straight edges or sides, by means of which, as a guide, straight lines may be drawn on paper, parchment, or other substance, by passing a pen or pencil along the edge. (See rule, and parallel ruler, under parallel.) When a ruler has the lines of chords, tangents, sines, etc., it is called a scale. See scale.
  • noun In engraving, a workman who operates a ruling-machine for ruling in flat tints, etc. See ruling-machine.
  • noun In line-engraving, a straight steel bar supported on cleats, to which a socket is so fitted that it slides evenly and steadily backward and forward.

from the GNU version of the Collaborative International Dictionary of English.

  • noun One who rules; one who exercises sway or authority; a governor.
  • noun 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).
  • noun See under Parallel.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun A (usually rigid), flat, rectangular measuring or drawing device with graduations in units of measurement; a rule; a straightedge with markings; a measure.
  • noun A person who rules or governs; a person who exercises dominion or controlling power over others.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun a person who rules or commands
  • noun measuring stick consisting of a strip of wood or metal or plastic with a straight edge that is used for drawing straight lines and measuring lengths


from Wiktionary, Creative Commons Attribution/Share-Alike License

to rule + -er.


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  • JM has encountered some managers who, given an inch, think they’re a ruler.

    May 25, 2011