Definitions of stimulus

1. That which excites or produces a temporary increase of vital action, either in the whole organism or in any of its parts; especially ( Physiol.), any substance or agent capable of evoking the activity of a nerve or irritable muscle, or capable of producing an impression upon a sensory organ or more particularly upon its specific end organ.

2. A goad: anything that rouses the mind, or that excites to action: a stimulant:- pl. STIMULI.

3. Anything that rouses to action.

4. Anything that rouses or excites.

5. Something which stimulates; a stimulant; a sting.

6. In med., that which produces a sudden but transitory increase of vital action; anything that excites to action; a stimulant; in bot., applied to stinging hairs with an irritating secretion at the base.

7. An agent which causes a body or some part of it to react when affected by it.