tom·cod (t?m?k?d?)n. pl. tomcod or tom·cods Either of two edible marine fishes, Microgadus tomcod of North American Atlantic waters or M. proximus of northern Pacific waters, closely related to and resembling the cod.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.tomcod (?t?m?k?d) n (Animals) a small fish resembling the codCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014