S: (n) instinct, inherent aptitude (inborn pattern of behavior often responsive to specific stimuli) "the spawning instinct in salmon"; "altruistic instincts in social animals"
S: (n) mind, head, brain, psyche, nous (that which is responsible for one's thoughts, feelings, and conscious brain functions; the seat of the faculty of reason) "his mind wandered"; "I couldn't get his words out of my head"