Mustache
Part of speech: noun
Definition: A growth of facial hair between the nose and the upper lip.
Example sentence: I inhaled Dickens as a kid, and I've always been fascinated by the Victorians. So many ridiculous objects they had! They created things like mustache cups, so you wouldn't wet your mustache when you were drinking tea. And eyebrow combs. What's happened to all the eyebrow combs? Marvelous things.
Moustache
Part of speech: noun
Definition: A growth of facial hair between the nose and the upper lip.
Example sentence: A moustache is actually the one thing I really can grow. One of the bad parts about my facial hair situation is that I can't grow sideburns. I'm happy to still have my own hair on my head, but I can't grow any sideburns. If you ever see me with sideburns, they're not real.