Source : Webster's Revised Unabridged Dictionary (1913)

Convexo-concave \Con*vex"o-con"cave\ (?or ?), a.
   Convex on one side, and concave on the other. The curves of
   the convex and concave sides may be alike or may be
   different. See {Meniscus}.

Source : WordNet®

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