a. Any of the cylindrical, keratinized, often pigmented filaments characteristically growing from the epidermis of a mammal.
b. A growth of such filaments, as that forming the coat of an animal or covering the scalp of a human.
2. A filamentous projection or bristle similar to a hair, such as a seta of an arthropod or an epidermal process of a plant.
3. Fabric made from the hair of certain animals: a coat of alpaca hair.
a. A minute distance or narrow margin: won by a hair.
b. A precise or exact degree: calibrated to a hair.
[Middle English her, from Old English hǣr.]
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