sensor

noun

1. a mechanical device sensitive to light, temperature, radiation level, or the like, that transmits a signal to a measuring or control instrument.
2. a sense organ.

noun

1. anything, such as a photoelectric cell, that receives a signal or stimulus and responds to it

n.1947, from an adjective (1865), a shortened form of sensory (q.v.). n.

1. A device, such as a photoelectric cell, that receives and responds to a signal or stimulus.
2. sense organ