Anatomy Any of the membranous tubes that form a branching system and carry blood to the heart.
A blood vessel.
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.
Zoology One of the horny ribs that stiffen and support the wing of an insect. Also called nervure.
Geology A regularly shaped and lengthy occurrence of an ore; a lode.
A long wavy strip of a different shade or color, as in wood or marble, or as mold in cheese.
A fissure, crack, or cleft.
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.
A transient attitude or mood.
A particular turn of mind: spoke later in a more serious vein.