zwit·ter·i·on (zw?t??r-???n, sw?t?-, tsv?t?-)n. 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 Indo-European roots) + Ion, ion (from Greek; see ion).]zwit?ter·i·on?ic (-?-?n??k) adj.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.zwitterion (?tsv?t?r?a??n) n (Chemistry) chem an ion that carries both a positive and a negative charge[C20: from German Zwitter hermaphrodite + ion] zwitterionic adjCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014zwit?ter?i?on (?zw?t ?r?a? ?n, ?sw?t-, ?tsv?t-) n. an ion with both a positive and a negative charge. [