nuclear isomers

https://doi.org/10.1351/goldbook.N04234
Nuclides having the same mass number and atomic number, occupying different nuclear energy states.
Source:
PAC, 1982, 54, 1533. 'Glossary of terms used in nuclear analytical chemistry (Provisional)' on page 1545 (https://doi.org/10.1351/pac198254081533)