Definition of hair

• n. - 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.
• n. - One the above-mentioned filaments, consisting, in invertebrate animals, of a long, tubular part which is free and flexible, and a bulbous root imbedded in the skin.
• n. - Hair (human or animal) used for various purposes; as, hair for stuffing cushions.
• n. - 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.
• n. - 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).
• n. - A spring device used in a hair-trigger firearm.
• n. - A haircloth.
• n. - Any very small distance, or degree; a hairbreadth.