metal detector

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A device that senses the presence of metal, especially.
• noun A handheld unit used in searching an area for coins or other metal objects.
• noun A gatelike structure through which a person passes, used in detecting concealed weapons such as guns and knives.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A hand-held device that uses electromagnetic induction to detect buried metal.
• noun A structure, similar to a doorway, through which people pass; an alarm is sounded if the person is carrying a metal object, as this may indicate a weapon.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun detector that gives a signal when it detects the presence of metal; used to detect the presence of stray bits of metal in food products or to find buried metal