If one were predisposed to find words listed in only one word reference--without using Mrs. B at all as one of the references--it would be a hard task, to say the least. This, of course, wasn't Mrs. B's purpose. I'm just saying.
Anyhow, the only word I know off the top of my head that I've seen in only one reference was ferrophiliac, although I know I've looked up some words here on AWAD that weren't in any reference I could put my hands on. Ferrophiliac will not be found in any dictionary that I know of to date; however, it will be found in The Random House Word Finder--or a title similar to that. I don't have the book here at the moment. You can google ferrophiliac, but you won't come up with any definition that approximates the one given in Random House [not dictionary, but word finder or whatever its actual name]. The connection to Mrs. B? Well, hardly any other than in this Random House book there are no footnotes to where the editor, now deceased, found his entries either. Many entries are common words--he wasn't going after the unusual and preposterous--but he doesn't note any individual references for where he found words. Too bad. I'd really like to know where he found ferrophiliac, but he's gone, same as Mrs. B. I will add his name here later today.
Edit: The correct title is Random House Word Menu, Stephen Glaier, editor
