nostalgia (n.)
Nostalgia is a fond feeling about the past. It started as the name of an illness.12
Johannes Hofer, a medical student at Basel, made the word for his dissertation of 1688 out of the Greek nostos, homecoming, and algos, pain. It was his Latin for the German Heimweh, homesickness, and he described it as a disease of the brain.12
The patients were often Swiss mercenaries serving abroad, set off by a remembered sight or a tune from home. They stopped eating and sleeping. It was taken seriously enough to be treated, and seriously enough to be written down as a cause of death.3
The word softened as the illness stopped being one. The ache stayed. The algos is half the word.12
A wave of nostalgia for the nineties.