backsight

Noun

 * 1) The rear sight of a firearm.
 * 2)  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)  A measurement of a previously shot point, used to set the angle to zero when occupying a new position.

Derived terms

 * blow a backsight

Translations

 * Bulgarian:

Verb

 * 1)  To shoot a backsight.