stimulus Definition

stimulus
noun stimuli

1. Something that acts as an incentive, inspiration, provocation, etc.

Thesaurus: inducement, provocation, motive, incentive, spur, impetus, catalyst; Antonym: discouragement.
2. Something, such as a drug, an electrical impulse, heat, light, etc, that causes a specific response in a cell, tissue, organ, etc.

Etymology: 17c: Latin, meaning ‘a goad'.