- Mustache and moustache are both correct spellings of the same word.
 - Mustache is the most common spelling in the United States.
 - Moustache is is used in other English-speaking countries.
 - Mustachio is usually spelled without an “o” in the first syllable, although in the UK it is commonly written as a plural: mustachios.
 
From the pencil mustache of John Waters to the bushy moustache of General Melchett, upper-lip hair comes in variety of styles.