I honestly have no idea so I'm compelled to say it's a blanket term with no substance used to label people as "deploreable" If someone could give me an actual definition, I would be grateful.

It's a bogeyman phrase, if you ask me. There aren't any actual principles associated with it, only certain attitudes. Being anti-establishment is apparently enough to qualify you as alt-right in some cases, but that isn't really a concrete principle.

As I understand it, it's a blanket term for predominantly internet dwelling new age conservatives, whether they be actual white nationalists à la Chateau Heartiste types, edgy /pol/ users, or just normal people fed up with the current republican party's take on conservatism. Generally, the term has a negative connotation due to the presence of the first two groups I listed.

The alt right is hard to define because it encompasses such a diverse group. There are genuine racists, there are conservatives who just don't like the establishment, etc. Essentially, the one common thing among all of them is that they're all fed up with the current system. But a blanket term such as "alt right" does not signify an entire group of people, as even they cannot agree on what they stand for.