Wiktionary
a whole 'nother
det. (context informal proscribed English) (alternative form of a whole nother English)
Usage examples of "a whole 'nother".
But that is a whole 'nother subject and a definite digression from the subject at hand, which is army trainin'.
I started out with a whole buncha guys in Freddy's Bel Air, and Teddy was with a whole 'nother bunch, but after we got run off by Miss Bitch, the rest of 'em wanted to go back to their barstools.