George Carlin's take:

"There's a condition in combat. Most people know about it. It's when a fighting person's nervous system has been stressed to it's absolute peak and maximum, can't take any more input. The nervous system has either snapped or is about to snap. In the first world war that condition was called shell shock. Simple, honest, direct language. Two syllables. Shell shock. Almost sounds like the guns themselves. That was 70 years ago. Then a whole generation went by. And the second world war came along and the very same combat condition was called battle fatigue. Four syllables now. Takes a little longer to say. Doesn't seem to be as hard to say. Fatigue is a nicer word than shock. Shellshock...battle fatigue. Then we had the war in Korea in 1950. Madison Avenue was riding high by that time. And the very same combat condition was called Operational Exhaustion. Hey we're upto 8 syllables now! And the humanity has been squeezed completely out of the phrase now. It's totally sterile now. Operational Exhaustion: sounds like something that might happen to your car. Then of course came the war in Vietnam, which has only been over for about 16 or 17 years. And thanks to the lies and deceit surrounding that war, I guess it's no surprise that the very same condition was called Post-Traumatic Stress Disorder. Still 8 syllables, but we've added a hyphen. And the pain is completely buried under jargon. Post-Traumatic Stress Disorder. I bet you, if we'd still been calling it shell shock, some of those Vietnam veterans might have gotten the attention they needed at the time. I bet you that."