Definitions

1. noun

Someone who sights or determines the position of something, especially in relation to the horizon.

“The surveyor used a theodolite as a sighter to measure the angle of elevation.”

2. verb

To measure or determine the position of something, especially in relation to the horizon.

“The astronomer sighted the star in the telescope to take its precise reading.”

3. noun

A device or instrument used for sighting or determining the position of something.

“The sighter on the rifle helped the marksman to aim accurately.”