zwit·ter·i·on (zwĭtər-ī′ən, swĭt-, tsvĭt-)
A molecule, especially an amino acid, containing a positively charged ion at one end and a negatively charged ion at the other.
[German : Zwitter, hybrid (from Middle High German zwitarn, from Old High German, from zwi-, twice; see dwo- in the Appendix of Indo-European roots) + Ion, ion (from Greek; see ION).]
zwit′ter·i·onic (-ī-ŏnĭk) adj.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. 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.