cub-
combining form 
or cubi- or cubo-
Etymology: New Latin, from Greek kyb-, kybo-, from kybos — more at cube 
1.
a. : cube 
< cuboctahedron >
< cubiform >
< cubomancy >
b. : of the third algebraic degree 
< cubinvariant >
< cubocubic >
2. cubo- : cuboid and 
< cubometatarsal >
or cubi- or cubo-
1.
a.
< cuboctahedron >
< cubiform >
< cubomancy >
b.
< cubinvariant >
< cubocubic >
2. cubo-
< cubometatarsal >