The Collaborative International Dictionary
Patagium \Pa*ta"gi*um\, n.; pl. Patagia. [L., an edge or border.]
(Anat.) In bats, an expansion of the integument uniting the fore limb with the body and extending between the elongated fingers to form the wing; in birds, the similar fold of integument uniting the fore limb with the body.
(Zo["o]l.) One of a pair of small vesicular organs situated at the bases of the anterior wings of lepidopterous insects. See Illust. of Butterfly.
n. 1 The thin membrane that extends between the limbs and body of a bat or of gliding mammals 2 A similar membrane between the body and wing of a bird