[ˈʌɪsəmə], (Noun)

Definitions:
- each of two or more compounds with the same formula but a different arrangement of atoms in the molecule and different properties

- each of two or more atomic nuclei that have the same atomic number and the same mass number but different energy states


Phrases:

Origin:
mid 19th century: from Greek isomerēs ‘sharing equally’, from isos ‘equal’ + meros ‘a share’