The noun hair has 6 senses (first 1 from tagged texts)
1. (59) hair -- (a covering for the body (or parts of it) consisting of a dense growth of threadlike structures (as on the human head); helps to prevent heat loss; "he combed his hair"; "each hair consists of layers of dead keratinized cells")
2. hair's-breadth, hairsbreadth, hair, whisker -- (a very small distance or space; "they escaped by a hair's-breadth"; "they lost the election by a whisker")
3. hair, fuzz, tomentum -- (filamentous hairlike growth on a plant; "peach fuzz")
4. hair, pilus -- (any of the cylindrical filaments characteristically growing from the epidermis of a mammal; "there is a hair in my soup")
5. haircloth, hair -- (cloth woven from horsehair or camelhair; used for upholstery or stiffening in garments)
6. hair -- (a filamentous projection or process on an organism)