Words can come from anywhere. They especially originate from contact with other cultures and in times of stress, like wars. I experienced this firsthand during the Vietnam era, when I was stationed in Thailand and heard how many Thai words my fellow airmen were using in their everyday conversation. Since I haven’t heard any of these words lately, I don’t know how many are actually considered part of today’s English, although nitnoy, meaning “a little bit,” may be an exception (https://www.urbandictionary.com/define.php?term=Nitnoy).
I was reminded of this when I ran across an article, “20 Slang Terms From World War I” by Paul Anthony Jones. Here are some examples —
Basket Case — World War I was especially difficult for the common soldier. Trench warfare with its incessant artillery barrages was only one hazard. Occasionally a body was so badly mutilated the soldier literally had to be removed from the battlefield in a basket. Today basket case has a less gruesome meaning: an inability to function normally.
Cooties — The bane of grade school children first appeared in the trenches in 1915 as a nickname for body or head lice. It is thought to have come from the coot, a species of water bird supposedly known for being infested with parasites.
Dingbat — This word actually came from the 19th century as a general placeholder for something you can’t recall, like thingamajig. During World War I, it came to mean a clumsy or foolish person, then was adapted by Australian and New Zealand troops to mean shell-shocked, nervous, or mad, as in “to have the dingbats” or “to be dingbats.” Speaking of which…
Shell-shock — Warfare, an uncivilized behavior in an otherwise civilized world, messes with the mind. Today we discuss the clinically-sounding Post Traumatic Stress Disorder (PTSD), but in World War I it was simply shell-shock. Although the term has been traced back as far as 1898, when it meant “subjected to heavy fire,” the Oxford English Dictionary has found the earliest usage in an article in The British Medical Journal dated January 30, 1915: “Only one case of shell shock has come under my observation. A Belgian officer was the victim. A shell burst near him without inflicting any physical injury. He presented practically complete loss of sensation in the lower extremities and much loss of sensation.” An updated definition is “A psychiatric condition characterized by fatigue caused by battle” (https://www.wordnik.com/words/shell%20shock).
The complete list is at https://getpocket.com/explore/item/20-slang-terms-from-world-war-i. The photo came from that site.