stimulus

stim·u·lus

noun \ˈstim-yə-ləs\

plural stim·u·li \-ˌlī, -ˌlē\

Definition of STIMULUS

1

: stimulant 1

2

: an agent (as an environmental change) that directly influences the activity of living protoplasm (as by exciting a sensory organ or evoking muscular contraction or glandular secretion) <a visual stimulus>