ve·na·tion / vēˈnāshən/ • n. Biol. the arrangement of veins in a leaf or in an insect's wing. ∎  the system of venous blood vessels in an animal.DERIVATIVES: ve·na·tion·al / -shənl/ adj.

venation
1. The arrangement of veins (vascular bundles) in a leaf. The leaves of dicotyledons have a central main vein (midrib) with side branches that themselves further subdivide to form a network (net or reticulate venation). The leaves of monocotyledons have parallel veins (parallel venation).

2. The arrangement of the veins in an insect's wing, which is often important in classification.

venation The pattern formed by the arrangement of the veins on the wings of insects. The veins are identified by a system of letters and numbers which allows their precise arrangement to be described. Venation is frequently used as a taxonomic character.

venation The arrangement of the veins or nerves of a leaf.