Jigjag, I think I am quite vigilant, but still slip up from time to time - see my 19.04 post! I definitely don't like 'math' as an answer without any reference to it being an Americanism. We are used to the various indicators - Ed, Bard, Morag... - when those are necessary for archaic or Scottish words, for example. I hadn't thought of 'mayo being an Americanism, and Chambers doesn't class it as such ('math' is described as 'North American'.)
I've never wondered about the first word of the title - and I refuse to do so now, but only because the whole thing has had too much of my attention this week!