Detector

·noun One who, or that which, detects; a detecter.

II. Detector ·add. ·noun An indicator showing the depth of the water in a boiler.

III. Detector ·add. ·noun Any of various devices for detecting the presence of electric waves.

IV. Detector ·add. ·noun A galvanometer, usually portable, for indicating the direction of a current.

detector
dētector, ōris, m. [detego], an uncoverer; trop., revealer (eccl. Lat.): creatoris, Tert. adv. ...

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.
Detector bar
·add. ·- A bar, connected with a switch, longer than the distance between any two consecutive wheels...

Webster's Dictionary of the English Language