Definitions of hair:

• noun:   a filamentous projection or process on an organism
• noun:   any of the cylindrical filaments characteristically growing from the epidermis of a mammal

  Example: "There is a hair in my soup"

• noun:   dense growth of hairs covering the body or parts of it (as on the human head); helps prevent heat loss

  Example: "He combed his hair"

• noun:   filamentous hairlike growth on a plant
• noun:   cloth woven from horsehair or camelhair; used for upholstery or stiffening in garments
• noun:   a very small distance or space

  Example: "They escaped by a hair's-breadth"

• name:  A surname (rare: 1 in 33333 families; popularity rank in the U.S.: #4603)