Source : Webster's Revised Unabridged Dictionary (1913)

Plane \Plane\, n. [F. plane, L. plana. See {Plane}, v. & a.]
   1. (Geom.) A surface, real or imaginary, in which, if any two
      points are taken, the straight line which joins them lies
      wholly in that surface; or a surface, any section of which
      by a like surface is a straight line; a surface without
      curvature.

   2. (Astron.) An ideal surface, conceived as coinciding with,
      or containing, some designated astronomical line, circle,
      or other curve; as, the plane of an orbit; the plane of
      the ecliptic, or of the equator.

   3. (Mech.) A block or plate having a perfectly flat surface,
      used as a standard of flatness; a surface plate.

   4. (Joinery) A tool for smoothing boards or other surfaces of
      wood, for forming moldings, etc. It consists of a
      smooth-soled stock, usually of wood, from the under side
      or face of which projects slightly the steel cutting edge
      of a chisel, called the iron, which inclines backward,
      with an apperture in front for the escape of shavings; as,
      the jack plane; the smoothing plane; the molding plane,
      etc.

   {Objective plane} (Surv.), the horizontal plane upon which
      the object which is to be delineated, or whose place is to
      be determined, is supposed to stand.

   {Perspective plane}. See {Perspective}.

   {Plane at infinity} (Geom.), a plane in which points
      infinitely distant are conceived as situated.

   {Plane iron}, the cutting chisel of a joiner's plane.

   {Plane of polarization}. (Opt.) See {Polarization}.

   {Plane of projection}.
      (a) The plane on which the projection is made,
          corresponding to the perspective plane in perspective;
          -- called also principal plane.
      (b) (Descriptive Geom.) One of the planes to which points
          are referred for the purpose of determining their
          relative position in space.

   {Plane of refraction} or {reflection} (Opt.), the plane in
      which lie both the incident ray and the refracted or
      reflected ray.