Q: Is it appropriate for someone to say, “That’s a whole nother issue.” Is “nother” a word?
A: No, “nother” is not a word. I discussed this in my first book (Woe Is I) because I found it so commonplace. You hear it a lot in speech but almost never see it in writing, which is true of so many bad usages.
“A whole nother” is probably a merging of “whole other” and “another.” It’s also been suggested that this error reflects a misunderstanding of the word “another” as two words: “a … nother.”