The furniture term horsehair refers to a type of upholstery material that is made from the hair of a horses tail or mane. It has historically been used as a stuffing material or fabric lining in traditional furniture. Horsehair is known for its durability and resilience, often used in high-quality upholstery due to its ability to retain its shape and provide support. It can also be woven into fabrics for use as upholstery covers or trim on furniture pieces. Also Haircloth.