mes·on (mĕzŏn′, mĕs-, mēzŏn′, -sŏn′, mā-)
Any of a class of subatomic particles that are both hadrons and bosons, are composed of a quark and an antiquark, participate in strong interactions, and have masses generally intermediate between those of leptons and baryons.
me·sonic (mĕ-zŏnĭk, -sŏn, mē-, mā-) adj.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.