A precision optical instrument for measuring horizontal and vertical angles, used in surveying and engineering.
測量士が経緯儀で角度を測っている。
The surveyor is measuring angles with a theodolite.
Compound of 経緯 (keii, 'longitude and latitude') and 儀 (gi, 'instrument'). The exact historical derivation is uncertain; the spelling is conventionally associated with the instrument's function.