ca·vet·to /kəˈvɛ(ˌ)to, kɑ-/
  Ca·vet·to n.  Arch. A concave molding; -- used chiefly in classical architecture.  See Illust. of Column.
  ◄ ►
  cavetto
       n : a concave molding shaped like a quarter circle in cross
           section
       [also: cavetti (pl)]