1. apparent change of position: an apparent change in the position of an object when the person looking at the object changes position
2. angle measuring star's distance from Earth: the angle between two imaginary lines from two different observation points meeting at an astronomical object, used to measure the object's distance from Earth
[Late 16th century. Via French< Greek parallaxis "alternation, angle between two lines" < parallassein "alter" < allos "other"]
