Main Entry: par·al·lax

Pronunciation: \ˈpa-rə-ˌlaks\

Function: noun

Etymology: Middle French parallaxe, from Greek parallaxis, from parallassein to change, from para- + allassein to change, from allos other

Date: 1580

: the apparent displacement or the difference in apparent direction of an object as seen from two different points not on a straight line with the object; especially : the angular difference in direction of a celestial body as measured from two points on the earth's orbit