8 letters · 10 points in Scrabble
noun inborn pattern of behavior often responsive to specific stimuli
adjective (followed by `with')deeply filled or permeated
originFrom Latin īnstīnctus, past participle of īnstinguō (“to incite, to instigate”), from in (“in, on”) + stinguō (“to prick”).
Etymology from Wiktionary, CC BY-SA 3.0