It's such a shame that dégringolade is such a fun word to say when it has a rather negative definition!
Dégringloade is a noun which refers to a rapid decline or deterioration (of strength, position, or condition). Basically, a downfall of some sort. A loved one who suffers from an abrupt decline in health could be said to be experiencing a dégringolade. It can also be used as a verb if one were to say that a person/government/relationship dégringoladed, but something about the -ed feels clunky to me!
You can probably tell that dégringolade has not been fully incorporated into English as it retains its French accent marking. The Middle French combination of "des" and "gringueler"
stem from the Middle Dutch verb "crinkelen" which meant 'to curl'. So there's some clear semantic drift happening here as we move from curling to a circular tumbling motion, to the idea of falling down and deteriorating. Check out alphaDictionary if you like poking about different word-histories!
Make sure you don't forget the first 'g', otherwise it sounds like a bad mix of Ringo and Kool-Aid.
–C