1. An inborn pattern of behavior that is characteristic of a species and is often a response to specific environmental stimuli: the spawning instinct in salmon; altruistic instincts in social animals.
2. A powerful motivation or impulse.
3. An innate capability or aptitude: an instinct for tact and diplomacy.

1. Deeply filled or imbued: words instinct with love.
2. Obsolete. Impelled from within.

[Middle English, from Latin īnstīnctus, impulse, from past participle of īnstinguere, to incite : in-, intensive pref.; see in-² + stinguere, to prick.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.