noun

1. the apparent change in the position of an object resulting from the change in the direction or position from which it is viewed
2. 1. the amount of angular degree of such change: the parallax of an object may be used in determining its distance from the observer because smaller angles indicate greater distance
   2. Astron. the apparent difference in the position of a celestial object with reference to a fixed background when viewed from two distant locations having a triangulated base line equal to the radius of the earth (diurnal parallax or geocentric parallax) or equal to the radius of the earth's orbit (annual parallax or heliocentric parallax)
3. the difference between the actual view covered by a camera lens and the apparent view seen through the viewfinder: this may be significant when the object is close to the camera

Etymology: Fr parallaxe < Gr parallaxis < parallassein, to vary, decline, wander < para-, para- + allassein, to change < allos, other: see else