giant water bug
See under water bug.
any of various aquatic bugs, as of the family Belostomatidae (giant water bug).
(loosely) a large cockroach, especially the American cockroach.
Origin of water bug
First recorded in 1740–50
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
any of various heteropterous insects adapted to living in the water or on its surface, esp any of the family Belostomatidae (giant water bugs), of North America, India, and southern Africa, which have flattened hairy legs
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012