vein

[count] : any one of the tubes that carry blood from parts of the body back to the heart — compare artery; see also varicose vein

[count] : any one of the thin lines that can be seen on the surface of a leaf or on the wing of an insect

[count] : a long, narrow opening in rock filled with gold, silver, etc.

[count] : a thin line or streak of material that has a different color or texture from the material that surrounds it

[singular] : a particular style, quality, etc.