Alidade

n.

1.

The portion of a graduated instrument, as a quadrant or astrolabe, carrying the sights or telescope, and showing the degrees cut off on the arc of the instrument

Noun	1.	alidade - surveying instrument consisting of the upper movable part of a theodolite including the telescope and its attachments Synonyms: alidad
	2.	alidade - surveying instrument used with a plane table for drawing lines of sight on a distant object and for measuring angles Synonyms: alidad

alidad, surveying instrument, surveyor's instrument, theodolite, transit