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I stayed up all night until sometime near noon the next day.

The word sometime is an adverb, but can I use it, as a noun, like above?.
Or should sometime be the two -word phrase some time?

Thanks
LiJ
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sometime adverb at some not specified or definitely known point of time <sometime last night> [m-w.com]

It's an adverb, not a noun, in your example.
sometime near noon, sometime last night, sometime tomorrow, sometime last week, etc.
CJ
Comments  
I get how the adverb someitme works!
Thanks, CJ.