Meaning & use
parallax
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Meanings
noununcountabletechnical
The way an object seems to shift position when you look at it from two different places, or the amount of that shift.
Grammar: Usually uncountable: talk about "parallax" in general, or "the parallax of" a particular object.
Patterns
- the parallax of something
- measure the parallax
- a parallax effect
Astronomers measure the parallax of nearby stars to work out how far away they are.
Hold up one finger and close each eye in turn; the jump you see is parallax.
The parallax between the two photographs showed that the camera had moved slightly.
nouncountable or uncountabletechnicalspecialist
In astronomy, the small change in a star's apparent direction seen from two points in Earth's orbit, used to find its distance.
Grammar: Often used with a number or unit: "a parallax of 0.1 arcseconds."
Patterns
- stellar parallax
- a parallax of something
- annual parallax
A star with a large stellar parallax must be fairly close to us.
The satellite recorded a parallax of less than a tenth of an arcsecond.
Early astronomers could not detect parallax because their instruments were not precise enough.
Common combinations
- stellar parallax
- Stellar parallax is the classic proof that Earth moves around the Sun.
- measure the parallax
- Surveyors measure the parallax between two sightings to fix a position.
- a parallax effect
- In the game, distant mountains move slowly to create a parallax effect.
- parallax error
- Read the scale straight on to avoid parallax error.
- the parallax of a star
- The parallax of a star shrinks as the star gets farther away.
Synonyms and how they differ
- displacement
- Use displacement for a general change in position; parallax is specifically the apparent shift caused by a change in viewpoint.
- shift
- Shift is the everyday word for a small movement; parallax is the technical term used in astronomy and optics.
Word family
- parallactic adjective
- Relating to parallax, as in a parallactic angle.
Commonly confused: parallax or paradox?
parallax vs paradox
Paradox means a statement that seems to contradict itself; parallax is about an apparent change in position. The two sound similar but have nothing to do with each other.
Practice
Which sentence uses "parallax" correctly?
Choose one answer.
Parallax is the apparent shift in an object's position when seen from different points, so it is used to measure distances to stars. The other options treat it as a pain, a payment, or an ingredient, none of which fits the meaning.
Make it your own
Write a sentence using “parallax”, then check it and compare it with the examples above.