A metal detector is the archway that beeps at metal on your person. Walk through the metal detector.
It works by inducing a current in any metal and sensing the field that comes back. A metal detector in a field is a different machine used to find coins and buttons.
1nounmetal detectorThe archway that beeps at metal on your person.
“The metal detector caught a coin he had forgotten about.”
metal detector is a device.
Metal plus detector; the principle was patented in the 1920s and reached airports in the 1970s.
metal + detector
Etymology from Wiktionary, CC BY-SA
Practised in Airport & Flying