sometimes it is sometimes it isnt. it depends upon a lot of things examples

the rules and laws in your location. every location has their own rules and laws about what is abusive and not.

what type of relationship is involved. there are some adult relationships situations where the more dominant one in the relationship is expected to humiliate the less dominant one. in this case its not considered abuse, its a consensual relationship.

whether or not the humiliation is a reaction not inflicted by others.. doing or saying something that ends up humiliating one self is not abuse.

someones physical ailments can be humiliating but not abusive depending on ones own views about their physical ailments.

here in NY it is abuse to humiliate a child over their problems ie call attention to their bed wetting, thumb sucking or other actions that may embarrass them.