vein
1.
2. Botany. One of the vascular bundles or ribs that form the branching framework of conducting and supporting tissues in a leaf or other expanded plant organ. Also called nervure.
3. Zoology. One of the horny ribs that stiffen and support the wing of an insect. Also called nervure.
4. Geology. A regularly shaped and lengthy occurrence of an ore; a lode.
5. A long, wavy strip of a different shade or color, as in wood or marble, or as mold in cheese.
6. A fissure, crack, or cleft.
7. A pervading character or quality; a streak: "All through the interminable narrative there ran a vein of impressive earnestness" (Mark Twain). See synonyms at streak.
8. a. A transient attitude or mood. b. A particular turn of mind: spoke later in a more serious vein.
verb
veined, veining, veins
2.
[Middle English veine, from Old French, from Latin vēna.]