I hate to play into Poe's law

And you should not introduce sarcasm into a serious discussion.

what is the difference between immoral and acceptable?

If you can rationalize murder as acceptable, you have defined murder as acceptable. It is not. It is immoral. But many people can rationalize any behavior.

You have basically said it is acceptable to murder Hitler.

I did not say that it was acceptable. I responded to a hypothetical question on going back in time and murdering Hitler to prevent the murder of millions. I said that I would do that if I believed that that doing it would in fact prevent the murder of those millions. I immediately noted that that action would be immoral. Read again my statement to that hypothetical:

I would murder Hitler to prevent the torture and murder of millions of people, but my action would not be moral. It would be murder and murder is immoral. Note that at the time I would have killed Hitler, he is not guilty of any crime. I am not executing a criminal. I am killing an innocent man. That is simply murder.

Hypotheticals are fraught with such problems. No one can go back in time to kill Hitler, so we are not discussing a real possibility.

If it is acceptable to perform an immoral act then I would think that calling it immoral is incorrect.

But I did not say it was acceptable to perform an immoral act.

If the correct and acceptable thing to do is to murder Hitler, then would it not be the moral thing to do?

It is neither correct nor acceptable. It is also impossible. And it would not be moral.

If you define morality as a set of actions that are acceptable, then anything beyond that set is always immoral. Or otherwise, if you define morality by the set of things that are immoral than only that specific set contains things that are always immoral. Most people do not agree that an exhaustive list of either moral or immoral things exist and that morality must be defined by simple rules of action to reach the most favorable outcome.

I see no reason to move this discussion of the Trolly Problem, where the only action available is to murder someone, to a discussion of an exhaustive listing of what is moral and what is immoral.

What do you believe defines murder as immoral?

It is self evident that murder is immoral.

To most of us it seems preposterous that you believe as you do because we see morality as a means to an end rather than a definition.

Therein lies the problem. You define the concept of morality as a means to an end rather than inherent in an action.

There is no basis for discussion if the terminology is malleable within the context of the discussion. That is to say, you have discarded the concept of morality other than as a means to an end, therefore, any discussion of morality with you must deteriorate into a meaningless discussion, since to you, morality has no meaning.