line of sight

American  

[lahyn uhv sahyt] / ˈlaɪn əv ˈsaɪt /

noun

1. Also called line of sighting.  an imaginary straight line running through the aligned sights of a firearm, surveying equipment, etc.

2. Astronomy. an imaginary line from an observer to a celestial body, coincident with the path traveled by light rays receivedfrom the body.

3. Radio. a straight line connecting two points sufficiently high and near one another so that the line is entirely above the surface of the earth.

4. Ophthalmology. line of vision.

5. sightline.

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line of sight British  

noun

1. the straight line along which an observer looks or a beam of radiation travels

2. ophthalmol another term for line of vision

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Etymology

Origin of line of sight

First recorded in 1550–60

Example Sentences

Always in each other’s line of sight, always negotiating space that didn’t exist.

From Los Angeles Times • Apr. 3, 2026

Additionally, Arcuri said he doesn’t think Intel would’ve retaken ownership of the Ireland fab if it didn’t have “a good line of sight over potential foundry wins.”

From MarketWatch • Apr. 2, 2026

For the entire tour Allen stood at the safety barriers, maintaining radio contact with his team and never leaving the band's line of sight.

From BBC • Mar. 21, 2026

Once that region rotates away from our line of sight, it disappears from view for another two weeks before returning.

From Science Daily • Jan. 13, 2026

I try to look at Autumn, but Tano moves his head to block my line of sight.

From "Kwame Crashes the Underworld" by Craig Kofi Farmer