hair

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

• noun Any of the cylindrical, keratinized, often pigmented filaments characteristically growing from the epidermis of a mammal.
• noun A growth of such filaments, as that forming the coat of an animal or covering the scalp of a human.
• noun A filamentous projection or bristle similar to a hair, such as a seta of an arthropod or an epidermal process of a plant.
• noun Fabric made from the hair of certain animals.
• noun A minute distance or narrow margin.
• noun A precise or exact degree.

from The Century Dictionary.

• To produce or grow hair.
• To form fine fibers, as syrup, when tested by dripping.
• noun One of the numerous fine filaments which more or less completely cover the skin of most mammals, and constitute the characteristic coat of this class of animals; any capillary outgrowth from the skin.
• noun The aggregate of the hairs which grow on any mammal; hairs collectively or in the mass; in the widest sense, a dermal coat or covering either of hair (specifically so called), wool, or fur; pelage; in common use, the natural capillary covering of a person's head: formerly sometimes in the plural.
• noun On animals, with the exception of most mammals, a filament; any fine capillary or hair-like outgrowth from the body or any part of it, but especially its surface; one of the objects which compose the hairiness, pubescence, or pilosity of an animal, or such objects collectively: used in both the singular and the plural: as, the hair or hairs of a caterpillar, that which clothes or those which clothe a lobster's gills, etc.
• noun In botany, an expansion of the epidermis, consisting of a single cell or of a row or number of cells.
• noun Haircloth; a garment of haircloth, especially a hair shirt used for penance.
• noun A cloth, mat, or other fabric of hair used for various purposes in the trades, as in the extraction of oils, manufacture of soap from cocoanut-oil, etc.
• noun Particular natural set or direction; course; order; drift; grain; character; quality.
• noun In mech., a locking spring or other safety contrivance in the lock of a rifle or pistol, which may be released by a very slight pressure on a hair-trigger.
• noun One of the polyps, as sertularians and others, which grow on oyster-shells. See graybeard, 3, and redbeard.
• Made of or stuffed with hair: as, hair jewelry; a hair mattress.
• Another spelling of hare.

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

• noun The collection or mass of filaments growing from the skin of an animal, and forming a covering for a part of the head or for any part or the whole of the body.
• noun One the above-mentioned filaments, consisting, in vertebrate animals, of a long, tubular part which is free and flexible, and a bulbous root imbedded in the skin.
• noun Hair (human or animal) used for various purposes.
• noun (Zoöl.) A slender outgrowth from the chitinous cuticle of insects, spiders, crustaceans, and other invertebrates. Such hairs are totally unlike those of vertebrates in structure, composition, and mode of growth.
• noun (Bot.) An outgrowth of the epidermis, consisting of one or of several cells, whether pointed, hooked, knobbed, or stellated. Internal hairs occur in the flower stalk of the yellow frog lily (Nuphar).
• noun A spring device used in a hair-trigger firearm.
• noun obsolete A haircloth.
• noun Any very small distance, or degree; a hairbreadth.
• noun [Obs.] in a rough and disagreeable manner; against the grain.
• noun (Ship Carp.) a molding which comes in at the back of, or runs aft from, the figurehead.
• noun (Anat.) cells with hairlike processes in the sensory epithelium of certain parts of the internal ear.
• noun a compass or divider capable of delicate adjustment by means of a screw.
• noun a glove of horsehair for rubbing the skin.
• noun a netted fillet for tying up the hair of the head.
• noun a line made of hair; a very slender line.
• noun (Zoöl.) any moth which destroys goods made of hair, esp. Tinea biselliella.
• noun a brush or pencil made of fine hair, for painting; -- generally called by the name of the hair used
• noun an iron plate forming the back of the hearth of a bloomery fire.
• noun a white perfumed powder, as of flour or starch, formerly much used for sprinkling on the hair of the head, or on wigs.
• noun (Zoöl.) any one of several species of eared seals which do not produce fur; a sea lion.
• noun haircloth for seats of chairs, etc.
• noun a shirt, or a band for the loins, made of horsehair, and worn as a penance.
• noun a strainer with a haircloth bottom.
• noun See Gordius.
• noun (Printing) the thinnest metal space used in lines of type.
• noun a delicate stroke in writing.
• noun a trigger so constructed as to discharge a firearm by a very slight pressure, as by the touch of a hair.
• noun of no value.