parallax Definition

parallax
noun parallaxes

1. physics.
The apparent change in the position of an object, relative to a distant background, when it is viewed from two different positions.
2. astron.
The angle between two straight lines joining two different observation points to a celestial body, used to measure the distance of stars from the Earth.

Derivative: parallactic
adj

Etymology: 16c: from Greek parallaxis change or alteration.