tse·tse fly (ts??ts?, ts??-)n. Any of various two-winged bloodsucking flies of the genus Glossina of sub-Saharan Africa that transmit the trypanosomes that cause sleeping sickness in humans and nagana in livestock.[Afrikaans, from Sotho (Tswana) tsêtsê.]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.tsetse fly (?ts?ts?) or tzetze flyn (Animals) any of various bloodsucking African dipterous flies of the genus Glossina, which transmit the pathogens of various diseases: family Muscidae[C19: via Afrikaans from Tswana]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014tset?se (or tzet?ze) fly` (?ts?t si, ?t?t-, ?tsi tsi, ?ti-) n. any of several bloodsucking African flies of the genus Glossina, including some that are vectors of trypanosomes that cause sleeping sickness and other diseases. Also called tset?se.[1860?65;