mustache

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The hair growing on the human upper lip, especially when cultivated and groomed.
• noun Something similar to the cultivated, groomed hair on the human upper lip, as.
• noun A group of bristles or hairs about the mouth of an animal.
• noun Distinctive coloring or feathers near the beak of a bird.
• noun Food or drink sticking conspicuously to the upper lip.

from The Century Dictionary.

• noun The beard worn on the upper lip of men; the unshaven hair of the upper lip: frequently used in the plural, as if the hair on each side of the lip were to be regarded as a mustache.
• noun . A long ringlet hanging beside the face, a part of a woman's head-dress in the seventeenth century.
• noun In zoology:
• noun Hairs or bristles like a mustache; whiskers; rictal vibrissæ mystaces.
• noun A mystacine, malar, or maxillary stripe of color in a bird's plumage.

from the GNU version of the Collaborative International Dictionary of English.

• noun That part of the beard which grows on the upper lip; hair left growing above the mouth.
• noun (Zoöl.) A West African monkey (Cercopithecus cephus). It has yellow whiskers, and a triangular blue mark on the nose.
• noun (Zoöl.) Any conspicuous stripe of color on the side of the head, beneath the eye of a bird.
• noun informal A stain or discoloration on the upper lip of a person.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A growth of facial hair between the nose and the upper lip.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun an unshaved growth of hair on the upper lip