joint                An articulation between two parts.

jugal area                             An area of the wing, less constantly present, lying behind the anal area and at the base of the wing posteriorly.  [see picture for Sphecinae]

jugum              Thin lobe projecting from the base of the forewing and overlapping the hind wing linking the two together, seen in moths In Lepidoptera the jugal area is produced into a projecting jugum, which is involved with coupling.