reactor

One that reacts to a stimulus.

A circuit element, such as a coil, used to introduce reactance.

A chemical reactor.

A nuclear reactor.

One who or that which reacts; specifically: In electricity, a reactive coil.

In experimental psychology, the observer in a reaction experiment; the person who executes a movement in response to a prearranged sensory stimulus.

A choking coil.

A nuclear reactor.

A person who behaves in response to a suggestion, stimulation or some other influence.