noun

• (countable) A pigmented filament of keratin which grows from a follicle on the skin of humans and other mammals.
  "And draweth new delights with hoary hairs."
• (uncountable) The collection or mass of such growths growing from the skin of humans and animals, and forming a covering for a part of the head or for any part or the whole body.
  "In the western world, women usually have long hair while men usually have short hair."
• (zoology, countable) 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.
• (botany, countable) A cellular 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)."

verb

• (transitive) To remove the hair from.
  "Now know ye, that in compliance with the said proviso, we the said John Cant and John Millar do hereby declare that our said invention of a new method of tanning leather is described in the manner following : that our method of preparing hides and skins by liming, hairing, fleshing, and baiting, is the same as that in use by the most experienced tanners; that is to say: All leather that is to be dressed or curried, we use the operation of what tanners call baiting, for this reason; that the leather when curried should carry a sufficient quantity of oil, and dry a good colour."
• (intransitive) To grow hair (where there was a bald spot).
  "He has haired up and healed over."
• (transitive) To cause to have or bear hair; to provide with hair
  "THE following classes of fiber are employed for hairing dolls : human hair, mohair, cross-bred wool, horsehair, hog-bristle, unspun cotton. Human hair is only used for hairing dolls of an extremely expensive class."