1The sight of a rifle or other weapon that is nearer the eye of the person aiming.
（步枪等武器的）表尺缺口
Example sentencesExamples
He ran his thumb along his rifle's backsight.
The first M91 / 30 rifles therefore, used the curved backsights of the old dragoon rifles.
The Model 41 has an undercut square post foresight, but its backsight attracted interest since it is mounted on a rib extending rearwards from the barrel.
To the left of the receiver is its backsight, in the form of a rearward, horizontal extension with a peep hole, controlled by a 2 3/16" diameter dial drum with gradations from 2[00] to 18[00] yards.
2Surveying A sight or reading taken backwards or towards the point of starting.
〔测绘〕后视
Example sentencesExamples
The first reading of almost any survey job should be a backsight onto a fixed point of reference, usually a benchmark of some sort.
If your party is recording corrected backsights be sure to read the upper scale if you are shooting a backsight.
This process is an example of one done without using backsights, still fairly common.
Support for a wide range of data styles, including ‘interleaved data’, backsights, underwater surveys performed with a depth gauge, and unsurveyed visual connections.
Taking backsights is a way of detecting errors and blunders in reading instruments.