vibrissa

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

• noun Any of the long stiff hairs that are located chiefly on the muzzle of most mammals and that function as tactile organs, as the whiskers of a cat.
• noun One of several long modified feathers located at the sides of the mouth of insect-eating birds.

from The Century Dictionary.

• In mammalogy, one of the long, stiff bristles which grow upon the upper lip and elsewhere upon the head of most mammals; a whisker, as of a cat.
• In ornithology, a rictal bristle; one of the special set of long, slender, bristle-like or bristly feathers, devoid of vexilla proper, which grow in a series along each side of the rictus or gape of the mouth of many birds, as flycatchers, goatsuckers, and others.
• In human anatomy, one of the hairs which grow in the nostrils.
• In entomology, one of the projecting lateral bristles on the upper border of the peristomium or mouth-cavity of certain Diptera.

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

• noun (Anat.) One of the specialized or tactile hairs which grow about the nostrils, or on other parts of the face, in many animals, as the so-called whiskers of the cat, and the hairs of the nostrils of man.
• noun (Zoöl.) The bristlelike feathers near the mouth of many birds.

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

• noun Any of the tactile whiskers on the nose of an animal such as a cat
• noun Any similar feather near the mouth of some birds

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

• noun a long stiff hair growing from the snout or brow of most mammals as e.g. a cat