Dictionary.com
Thesaurus.com

mesomerism

American  
[mi-zom-uh-riz-uhm, -som-] / mɪˈzɒm əˌrɪz əm, -ˈsɒm- /

noun

Chemistry.
  1. resonance.


Etymology

Origin of mesomerism

1925–30; meso- + -merism, on the model of isomerism, tautomerism