Mustache is the U.S. spelling of the word referring to hair on the upper lip. Moustache is the preferred spelling in all the main varieties of English from outside the U.S.
Mustachio, which resembles the Italian word for the facial hair but is spelled differently, was originally a variant of mustache, but it has long been used to refer to an especially luxuriant mustache.
The past-participial adjectives corresponding to these words are mustached, moustached, and mustachioed.
Lovell plotted to make Hitler’s mustache fall off and his voice turn soprano by injecting female hormones into the vegetables der Fuehrer ate. [Washington Post]
And of course there was my dad, a cop with a Tom Selleck mustache. [New York Times]
So I trained solo with Raul, my regal, mustached instructor, who on day one greeted me with a hearty “hola” and a nod to follow him through the stables. [Wall Street Journal]
Outside the U.S.
Many thought some moustaches made their owners look like porn stars. [Chronicle Herald (Canada)]
Outside, the moustached Mr Osbourne is still separated from the door by at least 100 people. [Independent]
It is tempting to think that the majority of this material is of the lame-storyline, large-moustache, Vaseline-lens variety. [Sydney Morning Herald]
It’s a quirky brand that sports a retro image of a chef with a luxuriant mustachio and a dreamy look in his eyes. [New York Times]
A week ago, you would’ve passed that shaggy, mustachioed grey mass of dog and sneered. [Globe and Mail]