No, an ad hominem is an argument that uses a personal attack to attempt to refute an opposing argument. So, if I say that your argument is invalid because you're a bootlicker, that's an ad hominem.

But if I say your argument is absurd, it has no merit whatsoever and it is nothing more than propagandist fantasy derived from nationalist zeal and a belief in American exceptionalism, and you're deranged for believing in such lunacy, then that's not an ad hominem.

Furthermore, there's the Fallacy fallacy, which states that just because an argument is fallacious, that it doesn't mean that it's a bad argument. There are plenty of ad hominems that are good arguments. For example, saying that nothing that comes out of Trump's mouth is worth listening to because he's a nazi is technically an ad hominem. It's also a good argument, because Trump is a nazi, and nothing that comes out of his mouth is worth listening to.