vein

noun

• 1any of the tubes forming part of the blood circulation system of the body, carrying mainly oxygen-depleted blood towards the heart. Compare with artery.
• (in general use) a blood vessel:he felt the adrenaline course through his veins
• (in plants) a slender rib running through a leaf or bract, typically dividing or branching, and containing a vascular bundle.
• (in insects) a hardened branching rib that forms part of the supporting framework of a wing, consisting of an extension of the tracheal system; a nervure.

• 2a fracture in rock containing a deposit of minerals or ore and typically having an extensive course underground: gold-bearing quartz veins
• a streak or stripe of a different colour in wood, marble, cheese, etc..
• a source of a specified quality: he managed to tap into the thick vein of discontent to his own advantage United have hit a rich vein of form

• 3 [in singular] a distinctive quality, style, or tendency:he closes his article in a somewhat humorous vein