What is Reflex-act?

Reflex-act definition and meaning on Dictionary terms:

Physiology. noting or pertaining to an involuntary response to a stimulus, the nerve impulse from a receptor being transmitted inward to a nerve center that in turn transmits it outward to an effector.
occurring in reaction; responsive.
cast back; reflected, as light, color, etc.
bent or turned back.
designating a radio apparatus in which the same circuit or part performs two functions.