Hamiltonian group
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In group theory, a Dedekind group is a group G such that every subgroup of G is normal. All abelian groups are Dedekind groups. A non-abelian Dedekind group is called a Hamiltonian group, after William Rowan Hamilton.
The most familiar (and smallest) example of a Hamiltonian group is the quaternion group of order 8, denoted by Q8. It can be shown that every Hamiltonian group is a direct product of the form G = Q8 × B × D, where B is the direct sum of some number of copies of the cyclic group C2, and D is a periodic abelian group with all elements of odd order.
