I realized that unsloped is another word for upright. So is it correct to say: The woman was unsloped. (Just as we might say the woman was upright).
I presume you are joking. ' Unsloped' is similar to 'upright' only when speaking of an object's physical angle with the horizon.
MM is right. I'd think that you can posssibly use erect instead of upright (because Homo Erectus comes to mind)
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You can use the word 'upright' to refer to a person's angle compared to the horizon. But you'd usually let the verb 'standing' communicate this on its own:

The woman was standing.

You'd usually only add the adverb 'upright' if you wanted to say that the woman was standing particularly straight, i.e. not slumped.

The woman was standing upright.

If you wanted to say that someone was 'unsloped' you would say:

The woman was lying flat.

You wouldn't just say 'the woman was lying' because that would mean the woman was not telling the truth.

Likewise, if one were to say 'the woman was upright', a reader (like Mr. Micawber) would typically interpret 'upright' to mean 'principled, honest, not corrupt'.

I can't think of any instance in which one would actually use the word 'unsloped'. It is not recorded anywhere in the full Oxford English Dictionary.
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