isomer
noun /ˈaɪsəmə(r)/
/ˈaɪsəmər/
- (chemistry) one of two or more compounds that have the same atoms, but in different arrangements
- (physics) one of two or more nuclei that have the same atomic number, but different energy states
Word Originmid 19th cent.: from Greek isomerēs ‘sharing equally’, from isos ‘equal’ + meros ‘a share’.