Main Entry: ¹con·cave

Pronunciation: \kän-ˈkāv, ˈkän-ˌ\

Function: adjective

Etymology: Middle English, from Latin concavus, from com- + cavus hollow — more at cave

Date: 15th century

1 : hollowed or rounded inward like the inside of a bowl
2 : arched in : curving in —used of the side of a curve or surface on which neighboring normals to the curve or surface converge and on which lies the chord joining two neighboring points of the curve or surface