alidade Meaning, Definition & Usage

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

WordNet

Al"i*dade noun
Etymology
LL. alidada, alhidada, fr. Ar. al-'idada a sort of rule: cf. F. alidade.
Definitions
  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 Whewell.

Webster 1913