Source : Webster's Revised Unabridged Dictionary (1913)

Concavo-convex \Con*ca`vo-con"vex\, a.
   1. Concave on one side and convex on the other, as an
      eggshell or a crescent.

   2. (Optics) Specifically, having such a combination of
      concave and convex sides as makes the focal axis the
      shortest line between them. See Illust. under {Lens}.

Source : WordNet®

concavo-convex
     adj : concave on one side and convex on the other with the
           concavity being greater than the convexity