упадък означава в английски

decadence▼(state of moral or artistic decline or deterioration)
noun
[UK: ˈdek.ə.dəns] [US: ˈdek.ə.dəns]

decline [declines]▼(downward movement, fall)
noun
[UK: dɪ.ˈklaɪn] [US: dɪ.ˈklaɪn]

degradation [degradations]▼(act of reducing in rank, character, or reputation, or of abasing)
noun
[UK: ˌde.ɡrə.ˈdeɪʃ.n̩] [US: ˌde.ɡrə.ˈdeɪʃ.n̩]

falloff▼(A reduction or decline)
noun
[UK: ˈfɒ.ˌlɒf] [US: ˈfɒ.ˌlɒf]

labefaction▼(act of shaking orweakening or the resulting state; overthrow, ruination)
noun
[UK: ˌlæ.bɪ.ˈfæk.ʃən] [US: ˌlæ.bʌ.ˈfæk.ʃʌn]