Where It Comes From
Denouement comes straight from French dénouement, "an untying," from the verb dénouer — "to undo a knot" (dé-, "un-," plus nouer, "to tie," from Latin nodus, "knot"). English writers borrowed it directly from French theater criticism around 1752, to describe the moment a play's tangled plot finally gets unknotted.
English never bothered translating it — which is exactly why, nearly 300 years later, this is still the one word in the English language most people can't decide whether to type with the little accent mark on the "e" or not. (Both spellings are correct.)
Say It Around the World
*Each language actually tells a different adoption story here. English kept the French word exactly as is, accent and all. Spanish never borrowed it — "desenlace" comes from "lazo" ("loop" or "lace"), a totally separate root, so Spanish landed on the same untying metaphor completely on its own. German splits the difference: everyday German uses "Auflösung" ("resolution"), but literary critics often just borrow "Dénouement" straight from French as their technical term — exactly like English did.
The next word describes something wonderful that happens by pure chance — the lucky break nobody planned for but everyone's glad happened anyway.