nounWord forms: plural ˈhorseˌflies
1. any of a number of large dipterous flies (family Tabanidae), the female of which sucks the blood
of horses, cattle, etc.
2. any of various other dipterous flies that bite or infest horses, esp. any of a family (Gasterophilidae) of botflies
Webster’s New World College Dictionary, Fourth Edition, compiled by the
editors of Webster’s New World Dictionaries. Copyright © 2010 by Houghton
Mifflin Harcourt. Published by Houghton Mifflin Harcourt. All rights reserved.
Word origin of 'horsefly'ME hors fleege