tȯˈtäməˌrizəm noun
( -s )
Etymology: taut- + -merism
: the phenomenon shown by a compound of behaving in chemical reactions as though the atoms in its molecule were arranged in more than one way expressible by different structural formulas, the two or more interconvertible isomeric forms not necessarily being isolable — called also dynamic isomerism ; see anionotropy , cationotropy , desmotropism , keto-enol tautomerism ; compare isomerism , resonance 5