Detector (noun)

1. A device or machine that detects or identifies the presence or existence of something.
2. A device that senses or registers the presence of something, especially sound, light, or heat.
3. An electronic device used to detect the presence of particular substances, especially in gas or liquid form.
4. A machine or instrument used to detect radiation or ionizing particles.
5. A piece of equipment used for the detection of concealed metal objects, especially for security purposes.

Origin:

Late 19th century: from detect + -or1.

Examples:

1. The detector at the airport scans bags for metal objects.
2. The smoke detector in the kitchen sounded an alarm when the toast caught fire.
3. The radiation detector in the laboratory helps in measuring the levels of radioactive substances.
4. The metal detector at the park helped in finding the lost coin.
5. The gas detector in the mines is essential for detecting the presence of harmful gases.