Man, a silent hater is just one of those dudes who stop by your house and they are all like, sitting in a clawed armchair, sippin' on their drinky-drink and just straight up muggin'! I know you know what I'm talking about. They just use their silence as another way of imposing their superiority.
Dude, this brother has just been hating on our joint all night! He's a silent hater to the fullest.
People who pretend to support you but secretly wish for you to fail; people who are haters, but don't speak up because they know the person they secretly 'hate' on has real talent and is going somewhere therefore they remain silent until they can find a reason to hate out loud.
This girl smiles in my face, but talks behind my back. She's a silent hater by definition.