: a crystal system characterized by three equal and interchangeable axes at equal angles to each other and usually classed as a division of the hexagonal system — compare tetragonal system.

How do you define crystal system?

Crystal system is a method of classifying crystalline substances on the basis of their unit cell. There are seven unique crystal systems. The simplest and most symmetric, the cubic (or isometric) system, has the symmetry of a cube.

What is rhombohedral structure?

In geometry, a rhombohedron (also called a rhombic hexahedron) is a three-dimensional figure with six faces which are rhombi. It is a special case of a parallelepiped where all edges are the same length.