surveyor's level; leveling instrument
A precision optical instrument used in surveying and construction to establish a horizontal line of sight. The term covers various types including dumpy levels and automatic levels.
The surveyor measured the elevation difference of the land using a leveling instrument.
Compound of 水準 (water level, standard) and 儀 (instrument). The term is a technical coinage for a surveying instrument that uses a spirit level or compensator to establish a horizontal line.