cheveu m (plural cheveux)
For the mass noun hair, use the plural des cheveux.
From Old French cheveu.
cheveu m (plural cheveux or cheveulx)
From earlier chevel, from Latin capillus, capillum.
cheveu m (oblique plural cheveus, nominative singular cheveus, nominative plural cheveu)
From Middle French cheveu, from Old French cheveu, from Latin capillus. See there for more details.