con·vex 
(kŏnvĕks′, kən-vĕks)
(kŏnvĕks′, kən-vĕks)adj.
Having a surface or boundary that curves or bulges outward, as the exterior of a sphere.
[Latin convexus; see wegh- in the Appendix of Indo-European roots.]
convex′ly adv.
convexleft to right: biconvex,
plano-convex, and
convexo-concave lenses