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(moral) decay; (social) decline; decadence; corruption; degeneration; deterioration
decline (in prosperity)
退廃的な雰囲気が漂う街だった。
It was a city with a decadent atmosphere.
文化の退廃を嘆く声が増えている。
More voices are lamenting the decline of culture.
退廃した社会に改革が求められた。
Reform was demanded in a decadent society.