a plant of the genus linum, esp. the l. usitatissimum, which has a single, slender stalk, about a foot and a half high, with blue flowers. the fiber of the bark is used for making thread and cloth, called linen, cambric, lawn, lace, etc. linseed oil is expressed from the seed.-the skin or fibrous part of the flax plant, when broken and cleaned by hatcheling or combing.