meal·worm (m?l?wûrm?)n. A larva of any of various darkling beetles, especially Tenebrio molitor, which infests flour and other grain products and is often used as food for birds and reptiles and as fish bait.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.mealworm (?mi?l?w??m) n (Animals) the larva of various beetles of the genus Tenebrio, esp T. molitor, feeding on meal, flour, and similar stored foods: family TenebrionidaeCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014meal?worm (?mil?w?rm) n. the larva of any of several darkling beetles of the genus Tenebrio, that infests granaries and is used as food for birds and animals. [1650?60] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.