An indicator or a sighting apparatus on a plane table, used in angular measurement.
A topographic surveying and mapping instrument used for determining directions, consisting of a telescope and attached parts.
A part of an optical or surveying instrument, consisting of the vernier, indicator, etc.
A surveying instrument consisting of a telescope mounted on a rule, used in topography.
(cartography, astronomy, surveying) A sighting device used for measuring angles.
Origin of alidade
- French from Medieval Latin alidada sighting rod from Arabic al-‘iḍāda the revolving radius of a circle al- the ‘iḍāda revolving radius (alternate form of ‘aḍud humerus) (from ‘aḍada to lop, cut (trees) ʕṣ́d in Semitic roots)
From American Heritage Dictionary of the English Language, 5th Edition