Yeah, that’s very sloppy terminology, but is quite common among demons, and wizards for that matter.
Technically, bound means you have a binding link to an Accursed Master.
Boggy was a bound demon, his AM screwed up and he’s now unbound.
Demons can have multiple masters, anyone who knows your name can bind you. In conflict the stronger binding spell usually wins, caveated to the strength of the AMs.
The very first time you are bound you are incarnated, and they almost always bind you at the same time.
Lenamare mentions this and glosses over it. He was trying to summon a previously bound demon. One that had been bound/incarnated but wasn’t currently bound to him (or least I think that’s what he said)
He was surprised to find a new completely unbound/never bound demon.
So technically there are three states
Never been bound (unbound/un-incarnated)
Not currently bound, but previously bound (unbound/currently unbound)
Bound to one or more AM’s. (bound)
I suppose in theory, you could have Never Been Bound Demon who has been incarnated, just not familiar with that happeing.
But in theory, a wizard could conjure and summon a previously never before bound demon, incarnate them and let them go.
Although, thinking on it, I don’t think that would work with the current spells they use. I am pretty sure all the incarnate spells have implied bindings in them, because why else would you do this?
So perhaps an Animage Summoner might be able to do this. Or a Demon Prince….