n An implement held vertically and viewed through an optical surveying instrument such as a
transit, used to measure distance in land surveying and construction
layout; an
engineer's rod,
surveyor's rod,
leveling rod,
ranging rod. The modern
(US) engineer's or surveyor's rod commonly is eight or ten feet long and often designed to extend higher. In former times a surveyor's rod often was a single wooden pole or composed of multiple sectioned and socketed pieces, and besides serving as a sighting target was used to measure distance on the ground horizontally, hence for convenience was of one rod or pole in length, that is, 5½
yards.