This word is doubly obscure, at least for me: Whilom (c. 1200), means having once been; former; once upon a time, erewhile, or at times past. It comes from the Old English hwilum, meaning at times, and is related to today’s while. It is doubly obscure for me because it has a similar formation to an equally obscure German word, weiland, meaning formerly, of yore. This German word is related to the modern weil, which is a false friend to the English word; the German word means because. The relation between the two is not a far stretch, as because implies that something happened in times past, once upon a time.
What do you think? Should we bring back whilom? I think, at any rate, we should start using of yore every chance we get!
Stephanie Huesler 
Yes, of yore is good. I also like erstwhile.
I’m with you for bringing back “of yore”, even though the spell checker changed it. I’m not sure I want to add whilom.
I’d only like whilom to make a comeback just to flummox people! LOL! 😉