decrudescence (day-croo-DEH-sense) n. a decrease in the progression or symptoms of a disease.
This term is derived from the Latin word crudescere, which means "to become worse." I came across decrudescence in a 19th century medical reference textbook that I purchased on eBay a few years ago. The passage was as follows:
After a period of several days, more or less, during which the symptoms mentioned, or some of them, have manifested themselves, the characteristic exanthem shows itself, and runs through a fixed cycle of development, acme, and decrudescence.The passage, which dealt with herpes zoster (shingles), seemed overly wordy, but the medical profession has a tradition of writing in ways that laypersons struggle to understand.
You would never catch a historian writing this way.