Douglas Harper's Etymology Dictionary
1900, from de- + compensation.
Wiktionary
n. 1 (context medicine English) The inability of a diseased or weakened organic system or organ to compensate for its deficiency, resulting in functional deterioration. 2 (context psychology English) The deterioration of cognitive or emotional functionality in a person who is distressed or who suffers from a psychological disorder.
Wikipedia
In medicine, decompensation is the functional deterioration of a previously working structure or system. Decompensation may occur due to fatigue, stress, illness, or old age. When a system is "compensated", it is able to function despite stressors or defects. Decompensation describes an inability to compensate for these deficiencies. It is a general term commonly used in medicine to describe a variety of situations.
Usage examples of "decompensation".
And though the decompensation I'd witnessed in the jail had seemed the farthest thing from fraud, could I be absolutely certain that I was immune from subterfuge?