from The American Heritage® Dictionary of the English Language, 4th Edition
- suffix Variant of -aholic.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- suffix Used to make nouns and adjectives describing someone who is addicted to something or feels a compulsion to do something.
Back-formation from alcoholic. (Wiktionary)
In so doing, the coiner made a new suffix out of -oholic.
But choco lent itself to the -oholic; why did Oates prefer the a?