The Collaborative International Dictionary of English v.0.48:

Imago \I*ma"go\, n.; pl. Imagoes. [L. See Image.]
   1. An image.
      [1913 Webster]

   2. (Zool.) The final adult, and usually winged, state of an
      insect. See Illust. of Ant-lion, and Army worm. Iman
      Imam