Unwillingness to accept(or tolerate) views, beliefs, or behavior that differ from one's own.

When we talk about intolerant behavior we are talking about actions and statements that are intended to demean others by design (and praise the inverse), this is pretty easy to define. Saying that a person's skin color or gender makes them lesser or to be despised is clearly intolerant, the person in context is clearly unable to change this as it is how they are. Whats funny about this is that the US Bill of rights is a statement on intolerance by design. It's meant to both give rights but also set tone.