1. a device that discovers or identifies the presence of something

Examples

• The smoke detector started beeping when the battery was low.
• Airport security uses metal detectors to screen passengers.
• The lie detector test showed inconclusive results.
• Scientists used a radiation detector to measure contamination levels.
• The motion detector turned on the lights automatically.
• Carbon monoxide detectors can save lives by warning of dangerous gas levels.
• The treasure hunter swept the beach with his metal detector.