Where does “кошмарный” come from?
кошмарный (Russian) comes from Russian кошма́р, from French cauchemar, from Middle French cauchemare, from Old French cauquemare, from Norman cauche, from Old French chauce, from Vulgar Latin calcea, from Latin calceus — small stone, pebble; gravel, rubble.
кошмарный (Russian): nightmarish; dreadful
Ancestry of “кошмарный”, step by step