-ˌrizəm noun
( -s )
Etymology: International Scientific Vocabulary isomer ic + -ism
1. : the phenomenon exhibited by two or more chemical compounds, radicals, or ions of containing the same numbers of atoms of the same elements in the molecule, radical, or ion and hence having the same molecular formula but differing in the structural arrangement of the atoms and consequently in one or more properties
the isomerism of the butyl alcohols
— compare geometric isomerism , optical isomerism , position isomerism , stereoisomerism , tautomerism
2. : the phenomenon exhibited by two or more nuclides of having the same mass numbers and the same atomic numbers but of differing in energy state and rate of radioactive decay — called also nuclear isomerism
3.
[probably from isomer ous + -ism ]
: the condition of having or being made up of corresponding parts or segments ; especially : the condition (as of a plant having the members of each floral whorl equal in number) of having two or more comparable parts made up of identical numbers of similar segments