1. any of the vascular bundles or ribs that form the branching framework of conducting and supporting tissues in a leaf or other plant organ • Syn: vein • Derivationally related forms: veinal (for: vein) • Hypernyms: vascular bundle, vascular strand, fibrovascular bundle • Hyponyms: midrib, midvein 2. one of the horny ribs that stiffen and support the wing of an insect • Syn: vein • Hypernyms: rib