Plane

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. [1913 Webster]

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. [1913 Webster]

3. (Mech.) A block or plate having a perfectly flat surface, used as a standard of flatness; a surface plate. [1913 Webster]

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. [1913 Webster]

{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 {Plane of reflection} (Opt.), the plane in which lie both the incident ray and the refracted or reflected ray. [1913 Webster]