Here is another new HEL Timeline entry.
New words that appear, words that entered common parlance, and words that gained new meanings during this war include: air raid, antiaircraft gun, ack-ack, aerobatic (used to describe pilots), ace (as in a pilot), tank, blimp, sector, bridgehead, dogfight, enlistee, fighter (as in an airplane), strafe, gadget (which existed earlier in naval slang but came into more general use now), machine-gun, mustard gas, barrage, storm-troops, dud, slacker, trench foot, Potemkin village, Soviet, u-boat, press officer, cootie (a body louse), shell shock, draftee, ROTC, war bride, and, interestingly, post-modern.
A series of films made in 1917, and preserved by the Wellcome library, show a variety of manifestations of what they meant by shell shock. You can find them here on YouTube or here on the Wellcome Library’s site with a list of what the clips include (follow either of these links to avoid stills from related videos about horrific physical injuries). The films don’t depict vivid physical injuries, though some depict physical manifestations such as spasms and frozen limbs.
Many didn’t believe the condition was real, or ascribed it to cowardice. The injury speaks to the particular and new kind of brutality that men endured in trench warfare. Several suffer from uncontrollable spasms while walking “following spinal concussion after burial”; another patient suffers from amnesia except for an uncontrollable response to the word “bombs” (see at 2:00 above). Here’s a further discussion of the injury from the BBC’s British History site.
According to the OED, the word first appears in a British medical journal in 1915. It’s in quotation marks, which would seem to indicate that while it existed verbally, no appropriate medical term was available. The book Soldier and Sailor Words and Phrases, first published in 1925, preserves a lot of language that came out of the war; its entry on shell shock says that after the war the term “psycho-neurosis” was adopted by the medical community to define the condition. This is a good example of how different communities deploy different terms even if they define identical objects or concepts, because words only make sense when they are embedded within the semantic associations provided by a community’s web of existing discourse. Later terms for the injury include combat stress disorder and post-traumatic stress disorder (PTSD). It undoubtedly afflicted soldiers from earlier wars; according to this PBS Frontline documentary about the term’s history, after the U.S. Civil war it was called “Soldier’s Heart.”
See: Baugh & Cable 300-01; Hughes, A History of English Words 376-82; Bryson, Made in America 296-297; Lerer ch. 18 (a chapter devoted to language and war, though mostly from WW2 and after); Cable, “British History Timeline,” and this page off of it.