A @M03997@ in which the principal product is indistinguishable (in the absence of @I03345@) from the principal reactant. The term includes both 'degenerate @I03130@ rearrangements' and reactions that involve @I03098@ transfer of atoms or groups ('degenerate @I03098@ rearrangements'): both are degenerate @I03295@. The occurrence of degenerate rearrangements may be detectable by @I03345@ or by dynamic NMR techniques. For example: the [3,3]@S05660@ of hexa-1,5-diene (Cope @R05194@): Synonymous but less preferable terms are '@A00528@', 'permutational @I03294@', 'isodynamic @T06446@', '@T06396@'.