(Late Latin, from the Greek
akëdeia,
a- +
këdos care, grief)
"abysmal apathy," an ecclesiastical term from late medieval monasticism, describing a state of acute depression particularly likely to affect those living a monastic existence. Acedia was considered a factor that could place monks and nuns at risk of demonic possession.
Source: Lewis Mumford. Interpretations and Forecasts (1973)