Source : Webster's Revised Unabridged Dictionary (1913)

Patagium \Pa*ta"gi*um\, n.; pl. {Patagia}. [L., an edge or
   border.]
   1. (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.

   2. (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}.