parallax

[ par-uh-laks ]

noun

1. the apparent displacement of an observed object due to a change in the position of the observer.
2. Astronomy. the apparent angular displacement of a celestial body due to its being observed from the surface instead of from the center of the earth diurnal parallax, or geocentric parallax or due to its being observed from the earth instead of from the sun annual parallax or heliocentric parallax. Compare parallactic ellipse.
3. the difference between the view of an object as seen through the picture-taking lens of a camera and the view as seen through a separate viewfinder.
4. an apparent change in the position of cross hairs as viewed through a telescope, when the focusing is imperfect.
5. Digital Technology. a 3D effect observed when images and other elements in the foreground of a screen move at a different rate than those in the background (often used attributively):

   parallax scrolling;

   Does this phone have parallax?

parallax

/ ˌpærəˈlæktɪk; ˈpærəˌlæks /

noun

1. an apparent change in the position of an object resulting from a change in position of the observer
2. astronomy the angle subtended at a celestial body, esp a star, by the radius of the earth's orbit. Annual or heliocentric parallax is the apparent displacement of a nearby star resulting from its observation from the earth. Diurnal or geocentric parallax results from the observation of a planet, the sun, or the moon from the surface of the earth

parallax

/ păr′ə-lăks′ /

1. A change in the apparent position of an object relative to more distant objects, caused by a change in the observer's line of sight towards the object. The parallax of nearby stars caused by observing them from opposite points in Earth's orbit around the Sun is used in estimating the stars' distance from Earth through triangulation.

Derived Forms

• ˌparalˈlactically, adverb
• parallactic, adjective

Other Words From

• par·al·lac·tic [par-, uh, -, lak, -tik], adjective
• paral·lacti·cal·ly adverb

Word History and Origins

Origin of parallax¹

First recorded in 1585–95; from Greek parállaxis “alternation, change of position” derivative of parallássein “to cause to alternate,” equivalent to para- + allássein “to change, alter, vary” (derivative of állos “other”) + -sis; para- ¹( def ), allo- -sis

Word History and Origins

Origin of parallax¹

C17: via French from New Latin parallaxis, from Greek: change, from parallassein to change, from para- ¹+ allassein to alter

Example Sentences

Worse, this parallax “offset” depends in complicated ways on objects’ positions, colors and brightness.

From Quanta Magazine

The astronomer Tycho Brahe didn’t detect any such stellar parallax and thereby concluded that Earth does not move.

From Quanta Magazine

Although a series of papers by Madore and Freedman’s team aren’t expected for a few weeks, they noted that the new parallax data and correction formula appear to work well.

From Quanta Magazine

One of the biggest sources of that uncertainty has been the distances to nearby stars — distances that the new parallax data appears to all but nail down.

From Quanta Magazine

They couldn't measure the parallax to the nearest star, so they would have no idea of stellar distances.

From Project Gutenberg

The most obvious and direct method is to determine the parallactic motion of the stars of known parallax.

From Project Gutenberg

The parallax decreases as the distance of the body increases.

From Project Gutenberg

Life becomes awful by its reaches: its span from zenith to nadir, by moral parallax.

From Project Gutenberg

The efforts to discover stellar parallax were, of course, still continued.

From Project Gutenberg