Different meanings for the insect wings and plants, see below!

Insect wing: sclerotized tubular structure supporting the insect wing. Veins can contain tracheae, blood vessels and nerve fibres. It can be generally distinguished between longitudinal veins originating from the wing base and cross veins joining longitudinal veins.
The structure of the wing venation can provide important diagnostical characters in insect taxonomy.
(wing.pct, Oph pinguis wing2.pct).

Plants: cell bundles containing vascular tissue and their supporting cells. Normally avoided by leaf-mining insects.

Alternative forms for vein : cross vein, crossvein, crossveins, venation.