Curious. One would expect the word 'moustache' to crop up slightly more frequently than once in four years, but apparently not: today I typed it in an email, and my Mac dutifully and sternly wiggled a red underline at me. Evidently the American spelling omits the 'o,' and I'd not previously had cause to correct Quern's dictionary. But this does rather beg the question: how is it that I have not written the word for so long? Perhaps I should grow one, to provide ample excuse?
On second thoughts: bad idea.
Do it!
There’s the other omitted o. Rapid googling confirms much usage of both mustachio and the parallelogram pushout, moustachio. Curiously only the former occurs in the context of wombats. If you can’t decide whether or not to grow one, why not try half? What was that in again? The American spelling makes this easier: one half’s an ache but the other’s a must.
moustache is half, to increase the face furniture to both sides of the upper lip you get moustaches - technically speaking
Granted, it tends to be a handlebar moustache, not a handlebars moustache.
Er.. more of a question is why you haven’t simply activated the British dictionary?