dissymmetry

Concise Oxford English Dictionary © 2008 Oxford University Press:
dissymmetry/dɪˈsɪmɪtri/

▶noun (pl. dissymmetries)

• 1 lack of symmetry.

• 2 the symmetrical relation of mirror images, as between the left and right hands.

– derivatives
dissymmetric adjective,
dissymmetrical adjective.