poilu

[pwah-loo; French pwa-ly] /ˈpwɑ lu; French pwaˈlü/
noun, plural poilus
[pwah-looz; French pwa-ly] /ˈpwɑ luz; French pwaˈlü/ (Show IPA)
1.
a French common soldier.
Origin
1910-15; < French, in earlier slang: tough individual, tough, brave, literally, hairy, haired; Middle French, Old French pelu (cf. plew) < Vulgar Latin *pilūtus, equivalent to Latin pil(us) hair + Vulgar Latin *-ūtus, for Latin -ātus -ate1 (e > oi by influence of poil hair < Latin pilus)
British Dictionary definitions for poilu

poilu

/ˈpwɑːluː; French pwaly/
noun
1.
an infantryman in the French Army, esp one in the front lines in World War I
Word Origin
C20: from French, literally: hairy (that is, virile), from poil hair, from Latin pilus a hair
Word Origin and History for poilu
n.

French private soldier, 1914, from French poilu, literally "hairy," from poil "hair," not of the head, but of beards, animal coats, etc., from Latin pilus (see pile (n.3)). In 19c. French the adjective had a secondary sense of "strong, brave, courageous" (Balzac).