I'd suspect that many people would agree with the statement that the antonym of "in" is "out", except for some peculiar situations perhaps. My natural chain of shower-thoughts led me to the word "within". The antonym of "within" from many online thesauri is "outside".
This seemed logical to me, but if you consider the relationship between "outside" and "inside", being antonyms, only the prefix [in-, out-] change to reverse the meaning of the words. Shouldn't the same principle of changing the [in-, out-] to reverse the meaning hold true to the word "within"?
I suspect many people will say that "within" is a synonym of "inside", thus justifying the antonym "outside" but is there something more to this?
Thanks in advance.