parallax

noun

par·​al·​lax ˈper-ə-ˌlaks 

ˈpa-rə-

: 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

Examples of parallax in a Sentence

Recent Examples on the Web

In the past few years these measurements have been replicated by many studies and further refined with the aid of the European Space Agency Gaia parallax observatory to 73 ± 1. —Marc Kamionkowski, Scientific American, 15 Oct. 2024

To eliminate parallax errors, the minute and second hands are thoughtfully curved at the ends, a feature on all of Hanhart’s watches. —Bhanu Chopra, Forbes, 4 Sep. 2024

Astronomers use parallax to determine the distance of stars. —Stefanie Waldek, Travel + Leisure, 7 Apr. 2024

Our brain automatically interprets the discrepancy (or parallax) as depth. —Stefanie Waldek, Travel + Leisure, 7 Apr. 2024

Word History

Etymology

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

First Known Use

1580, in the meaning defined above

Kids Definition

parallax

noun

par·​al·​lax ˈpar-ə-ˌlaks 

: the apparent shift in position of an object as seen from two different points not on a straight line with the object

Medical Definition

parallax

noun

par·​al·​lax ˈpar-ə-ˌlaks 

: 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

motion parallax governs the way objects appear to move when the eyes or head are shifted

—Edmund Andrews