Source : Webster's Revised Unabridged Dictionary (1913)

Cavetto \Ca*vet"to\ (k[.a]*v[e^]t"t[-o]), n. [It. cavetto, fr.
   cavo hollow, L. cavus.] (Arch.)
   A concave molding; -- used chiefly in classical architecture.
   See Illust. of {Column}.

Source : WordNet®

cavetto
     n : a concave molding shaped like a quarter circle in cross
         section
     [also: {cavetti} (pl)]