1. An innate, typically fixed pattern of behavior in animals in response to certain stimuli: "predatory instincts".
2. A natural or intuitive way of acting or thinking: "rely on your instincts".
For Gwen the pitoodle, instinct somehow means building nests
I have a problem in that I usually don't feel hungry until my blood sugar crashes. It's nice to have this around for those times and, since those times happen more often during marathon training, maybe, this time, I'm actually prepared.
Speaking of instincts - here is a Simba who is prepared to exercise them while I type.