noun

1. 1. any blood vessel that carries blood from some part of the body back toward the heart
   2. loosely any blood vessel
2. any of the riblike supports strengthening the membranous wings of an insect
3. any of the bundles of vascular tissue forming the framework of a leaf blade
4. a more or less continuous body of minerals, igneous or sedimentary rock, etc., occupying a fissure or zone, differing in nature from the enclosing rock, and usually deposited from solution by circulating water
5. lode (senses 1 & 2)
6. a streak or marking of a color or substance different from the surrounding material, as in marble or wood
7. 1. any distinctive quality or strain regarded as running through one's character, or a speech, writing, etc. a vein of humor in the essay
   2. course or tenor of thought, feeling, action, etc.
8. a temporary state of mind; mood speaking in a serious vein

Etymology: ME veine < OFr < L vena

transitive verb

1. to streak or mark with or as with veins
2. to branch out through in the manner of veins