Pronunciation: (al'i-dād"),[key] —n.Survey. 1. (in plane-tabling) a straightedge having a telescopic sight or other means of sighting parallel to the straightedge.
2. the entire upper part of a theodolite or transit, including the telescope, its supports, the level vials, the circle-reading device, and the spindle. Also,al•i•dadPronunciation: (al'i-dad").[key]