cavetto
noun
ca·vet·to kə-ˈve-(ˌ)tō 
kä-
plural cavetti kə-ˈve-tē
kä-
: a concave molding having a curve that approximates a quarter circle see molding illustration
Word History
Etymology
borrowed from Italian, from cavo "hollow, concave" (going back to Latin cavus) + -etto, diminutive and hypocoristic suffix — more at hole entry 1
First Known Use
1664, in the meaning defined above