mə̇ˈtaməˌrizəm noun
( -s )
1. : isomerism especially of chemical compounds of the same type (as butylamine and methyl-propyl-amine)
2. : the condition of having or the stage of evolutionary development characterized by a body made up of metameres that is usually held to be an essential prelude to the differentiation of the more highly organized animals (as arthropods and vertebrates) through the disproportionate development and elaboration of some segments together with the coalescence, reduction, or loss of others