What does "alidade" mean?

A type of sighting device used for measuring angles.

Alidade

Common synonyms include: alidad, historic instrument, map table instrument, sighting instrument, sighting rule, telescopic alidade.

/ˈæ.lɪ.deɪd/ noun

noun ·Rare ·Advanced level

Noun

1
A type of sighting device used for measuring angles.
2
surveying instrument used with a plane table for drawing lines of sight on a distant object and for measuring angles wordnet
3
surveying instrument consisting of the upper movable part of a theodolite including the telescope and its attachments wordnet

From French alidade, from Spanish alidada, from Arabic العِضَادَة (al-ʕiḍāda), perhaps from عَضُد (ʕaḍud, “upper arm”).