an envelope containing an explosive device designed to detonate when the envelope is opened by the recipient.
Origin of letter bomb
First recorded in 1945–50
Also called mail bomb.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for letter bomb
a thin explosive device inside an envelope, detonated when the envelope is opened
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