Main Entry: ¹in·stinct 

Pronunciation: \ˈin-ˌstiŋ(k)t\

Function: noun

Etymology: Middle English, from Latin instinctus impulse, frominstinguere to incite; akin to Latin instigare to instigate

Date: 15th century

1 : a natural or inherent aptitude, impulse, or capacity 
2 a : a largely inheritable and unalterable tendency of an organism to make a complex and specific response to environmental stimuli without involving reason b : behavior that is mediated by reactions below the conscious level