line of sight

noun

1. Also called line of sighting. 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.

line of sight

noun

1. the straight line along which an observer looks or a beam of radiation travels
2. See line of vision
   ophthalmol another term for line of vision

Word History and Origins

Origin of line of sight¹

First recorded in 1550–60

Example Sentences

I'm inclined like everybody else to consider perception on a line-of-sight basis instead of on a sort of all-around grasp.

From Project Gutenberg

As needed, line and non-line-of-sight weapons of near pin-point accuracy would be delivered across the entire area of operation.

From Project Gutenberg

Radio contact is strictly line-of-sight inside a hunk of metal.

From Project Gutenberg

There were other instruments in other line-of-sight positions, very far away.

From Project Gutenberg

He started the fuel pumps winding up, and swung the ship to point normal to the line-of-sight to the jammer.

From Project Gutenberg