Tom can't grow a mustache yet. - Tom can't grow a moustache yet.
Women like men with mustaches. - Women like men with moustaches.
an unshaved growth of hair on the upper lip; "he looked younger after he shaved off his mustache"
A man's moustache is the hair that grows on his upper lip. If it is very long, it is sometimes referred to as his moustaches. He was short and bald and had a moustache. + moustached mous·tached three burly, moustached middle-aged men. hair that grows on a man's upper lip beard