reflector

Concise Oxford English Dictionary © 2008 Oxford University Press:
reflector/rɪˈflektə(r)/

▶noun

• 1 a piece of reflective material, e.g. a red one on the back of a motor vehicle.

• 2 an object or device which reflects radio waves, seismic vibrations, sound, or other waves.

• 3 a reflecting telescope.