alidade


alidade
alidade [al′idad΄al′i dād΄]
n.
[Fr < Sp alidada < Ar al ʿ iḍāda, two sides or sideposts < ʿ aud, upper arm]
1. a part of an optical or surveying instrument, consisting of the vernier, indicator, etc.
2. a surveying instrument consisting of a telescope mounted on a rule, used in topography: Also alidad [al′idad΄]

English World dictionary. . 2014.