Not accepted in the recent PROSTHETIC game.  Dictionaries list it as a plural noun, but it's one of those strange plurals that don't have a singular form (heroic being an adjective rather than a noun).  So, I think it qualifies for inclusion.

It's common to me.  I reckon plenty of non-Americans know the word.

Games with a Q in them are good too!

I tried bodhi (the state of enlightenment in Buddhism) unsuccessfully in the recent ********* game.  It's listed (without a capital B) in various dictionaries including Merriam-Webster, Collins and dictionary.com, as well as in numerous reference works on Buddhism and religion in general. 

(Edited by AW to remove key word spoiler)

Napoleon can be both a proper noun (the famous historical figure) and a regular noun (spelt without a capital N) with several meanings, including:

a pastry consisting of thin layers of puff paste interlaid with a cream or custard filling.
a former gold coin of France, equal to 20 francs and bearing a portrait either of Napoleon I or of Napoleon III.
a card game in which the players bid for the privilege of naming the trump, stating the number of tricks they propose to win.
a bid in this game to take all five tricks of a hand.

The question is how common the regular noun is.

Found by only 18 of 308 players in the recent INEVITABLY game.  Certainly not common to me, or very many others it would seem.

Maybe the weather reporter meant it literally (i.e. a blast of cold air coming up from Antarctica).

I'd have thought it was more likely to be an adjective describing a person or animal that has not found a mate.