Literally: excelling, surpassing, or going beyond natural inward impulse to action that is unconscious, involuntary, or unreasoning, whether bodily or mental, with a distinct understanding of the end or object to be accomplished.
Some see this as the definition of humanity, that which distinguishes us from the animals: our ability to apply higher reasoning to act in directions other than those towards which instinct pressures us.
Most of us resist our instinctive reactions to foods like refined sugar, fat, an others we 'know' are 'bad for us'. When faced with a sugar bowl, we do not mindlessly consume all we can get our hands on, as many animals do in the laboratory. Later, we control the urge to defacate, something we are taught from when we were very young. Of course, we teach dogs this trick, but we don't think they ever understand why they shouldn't go in the house.
We also control the urge to mate or masturbate. Unlike dogs, cats, or any other animal interested in continuing its species, we easily overcome that biological imperative. When a member of society cannot control this instinct, for instance by raping someone, we often describe that person's behavior as animalistic.