concavity
con.cav.i.ty \ka:n-'kav-*t-e-\ n 1: a concave line, surface, or space : HOLLOW 2: the quality or state of being concave
con.cav.i.ty \ka:n-'kav-*t-e-\ n 1: a concave line, surface, or space : HOLLOW 2: the quality or state of being concave