costa, costae, costal, costate

1-(wing) The outer margin of the wing when it is outspread.

2-A longitudinal raised rib.

Related terms:

costal vein - The first principal nerve of the wing, it is the strong vein which runs along the upper edge of each wing, either on the extreme edge or just below it (Jardine).

costal margin (also costal region) - The wings of insects present a somewhat triangular figure; the upper portion or side of this figure is called the costal region; the outer portion or side, the exterior region; the lower portion or side, the interior region, and the central portion, the central region. These regions have no precise or definite limits, but are somewhat vague and ideal (Jardine). See diagram:

costate - Furnished with costae, longitudinal raised ribs, as in costate elytra: