trench mortar definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
any of various portable mortars for shooting projectiles at a high trajectory and short range
trench mortar definition by American Heritage Dictionary
A mortar usually ranging from 3 to 9.45 inches in caliber, designed for use in forward positions, especially in trenches.