What does parallax mean?
Parallax is the apparent change in the position of an object when it is viewed from different points, rather than a change in the object itself. The best-known application is stellar parallax: as Earth travels around the Sun, nearby stars appear to shift slightly against the more distant background, allowing astronomers to calculate their distances. In photography, illustration, and digital imaging, parallax describes the relative movement of foreground and background elements and can create a convincing sense of depth. The word is generally formal or technical, though it is now familiar to many people through digital photography and computer graphics. Its central idea is useful whenever a viewpoint changes: what appears to move may actually be the observer's position, or the difference between how nearby and distant objects are seen.
nounThe apparent displacement of an object viewed from different positions, especially the apparent change in the position of a distant object when observed from different points on Earth. In visual art and photography, the term can also refer to the relative shifting of foreground and background elements that creates a sense of depth.
- The apparent displacement of an object when viewed from different positions, especially from different points on Earth.
- A visual or photographic effect in which foreground and background elements shift relative to one another, creating depth or an impression of movement.
- A change in viewpoint or apparent position resulting from movement, especially in digital or optical technology.
"Astronomers measure the distance to nearby stars by detecting the tiny change in their apparent position as Earth moves around the Sun."
"The image shifted slightly as the camera moved, revealing a small parallax between the foreground and background."
"The survey corrected for parallax before combining observations from telescopes at different locations."
Usually uncountable when referring to the general phenomenon or a measurement, but “parallaxes” is used for separate instances, observations, or effects.
"The astronomers measured the parallaxes of several nearby stars."
The nearest stars reveal themselves through a tiny yearly wiggle called parallax, letting astronomers measure distances across space without leaving Earth.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does parallax come from?
The word comes from Greek parallaxis, meaning a change of viewpoint or an alternating appearance, and ultimately from para-, meaning beside or near, and allaxis, meaning a change to another axis. English borrowed it in the early 17th century for the apparent displacement of celestial objects. The same Greek elements are also reflected in words such as parallel and allometry, although their modern meanings have developed independently.
Related word forms
How parallax is actually used
In astronomy and surveying, the word is technical and refers to an apparent positional change caused by observing from different locations. In visual design, photography, and digital media, it is used more broadly for the relative movement or depth effect between image layers. The term is usually uncountable in technical contexts, although “parallaxes” is possible when referring to separate measurements or effects.