seed-hair fibre obtained from the outer shell, or husk, of the coconut, the fruit of Cocos nucifera (coconut palm), a tropical plant of the Arecaceae (Palmae (palm)) family. The coarse, stiff, reddish brown fibre is made up of smaller threads, each about 0.01 to 0.04 inch (0.03 to 0.1 centimetre) long and 12 to 24 microns (a micron is about 0.00004 inch) in diameter, composed of lignin, a woody plant substance, and cellulose. Sri Lanka is the centre of coir preparation, with hand processing, believed to produce a superior fibre, concentrated in the southwestern part of the island.

The processed fibres, ranging from about 4 to 12 inches (10 to 30 centimetres) in length, are light in weight, brittle, strong, and elastic, with a tendency to curl. They are resistant to abrasion and can be dyed. They are used to make brushes, are woven into matting, and are spun into yarns for marine cordage and fishnets.