Definition of "backsight" in English

noun

1. The rear sight of a firearm.

2. (surveying) A measurement or reading taken back towards a point of known elevation, used to calculate the height of the surveying instrument (theodolite, transit, total station).

3. (surveying) A measurement of a previously shot point, used to set the angle to zero when occupying a new position.

verb

1. (surveying) To shoot a backsight.