noun 1. a. the hair that a man has let grow out on his upper lipsometimes used in the plural in reference to the two halves of this growth
b. hair growing on the upper lip ⇒ at fourteen he's already getting a mustache
Webster’s New World College Dictionary, Fourth Edition, compiled by the
editors of Webster’s New World Dictionaries. Copyright © 2010 by Houghton
Mifflin Harcourt. Published by Houghton Mifflin Harcourt. All rights reserved.
Word origin of 'mustache'Fr moustache < It mostacchio, mustache < MGr mustaki < Gr mystax, upper lip, mustache < mastax, a mouth, jaws < IE base *menth- > mouth