Dictionary
Dear' John'
Informal.
1. a letter from a woman informing her boyfriend or fiancé that she is ending their relationship or informing her husband that she wants a divorce:
Nothing is worse for a soldier's morale than getting a Dear John.
2. any letter terminating a relationship.
Also called Dear' John' let"ter. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.