- an imaginary straight line running through the aligned sights of a firearm, surveying equipment, etc.
- an imaginary line from an observer to a celestial body, coincident with the path traveled by light rays receivedfrom the body.
- a straight line connecting two points sufficiently high and near one another so that the line is entirely above the surface of the earth.
- line of vision.
- sightline.
- the straight line along which an observer looks or a beam of radiation travels
- ophthalmol another term for line of vision
