Definition of vein

• n. - One of the vessels which carry blood, either venous or arterial, to the heart. See Artery, 2.
• n. - One of the similar branches of the framework of a leaf.
• n. - One of the ribs or nervures of the wings of insects. See Venation.
• n. - A narrow mass of rock intersecting other rocks, and filling inclined or vertical fissures not corresponding with the stratification; a lode; a dike; -- often limited, in the language of miners, to a mineral vein or lode, that is, to a vein which contains useful minerals or ores.
• n. - A fissure, cleft, or cavity, as in the earth or other substance.
• n. - A streak or wave of different color, appearing in wood, and in marble and other stones; variegation.
• n. - A train of association, thoughts, emotions, or the like; a current; a course.
• n. - Peculiar temper or temperament; tendency or turn of mind; a particular disposition or cast of genius; humor; strain; quality; also, manner of speech or action; as, a rich vein of humor; a satirical vein.
• v. t. - To form or mark with veins; to fill or cover with veins.