Often one will hear the phrase that’s a whole nother kettle of fish, but is “nother” actually grammatical? If not, what would the correct way of saying it be?
I always took this usage to be purely humorous. Certainly I’ve only ever used it as such.
It’s definitely not a contraction of “a whole another” – no one would say that (I hope). It’s simply taking “another” and putting “whole” in the middle as if it was originally “a nother kettle of fish”, which of course we know it’s not.
The correct version is simply “a whole other”.
EDIT: some more discussion on this here: “A whole nother” way of looking at things