convexity
con.vex.i.ty \k*n-'vek-s*t-e-, ka:n-\ n 1: the quality or state of being convex 2: a convex surface or part
Webster's English Dictionarycon.vex.i.ty \k*n-'vek-s*t-e-, ka:n-\ n 1: the quality or state of being convex 2: a convex surface or part