In Hebrew it says "murder" (from the root RṢḤ). Its distinct from killing (from the root HRG). And the difference, as you basically said, is killing someone who G-d did say should be judged for death is unlawful and by extension - murder. While killing someone who G-d did say should be judged for death is lawful and not murder.
So abortion would not be murder.
Abortion would be distinct from murder because, um, er, God did say fetus should be judged for death, and/or because it is lawful, therefore not possibly murder.
All we need then are laws that killing sprees are not murder, and they are not, right?
Because if the State ever says there are lawful, then it can't possibly be murder, right? It is obviously still killing, but because it's not unlawful, it can't possibly be murder, right? Right now killing sprees when not done by the State, and not considered lawful, are murder. But if we just change the State's laws, then not murder, right? Just trying to get at the understanding of difference between murder and killing.
Which technically we already have such laws in place, just arbitrarily applied.
Like if the state (or country) engages in activities that lead to collateral damage (where many non combative enemies are killed), this is not to be framed, ever, as murder. It is obviously killing, but because the State (legally) authorized itself to engage in the action, and those people died as a result, the State's killing spree is not to be seen as murder. I would think abortion, being lawful, is another killing spree occurring, and is not murder. Of course if we killed a whole bunch of born babies, that would probably be seen as murder. But if we could just change it to the State supporting this, then not murder. Still a killing spree, but not murder. Or if the State engages in Capital punishment, and during that whole period of time it ends up killing people that didn't actually commit the crime that the State thought it proved, beyond a reasonable doubt, that wouldn't be murder, because they were lawfully killed. So, a killing spree, even with Capital punishment working, but not murder because it was 'lawful.'
All of which goes back to the original inconsistency I brought up, and why attributing 'okay to kill humans in some instances' is about as insane as one can get, especially with context of 'do not kill' being a commandment. But as long as humans are feeling righteous enough to understand difference between murder and killing, then really, c'mon, how could this ever pose any problems for humanity? One would think God would be happy with all the killing we've done in his (cough cough) name.
Before I really was looking for a debate, but kinda knew it would be based on feeble logic. Now, I still want it, but managed to produce a rant that if you find room to offer rebuttal, then good luck.