noun, feminine/de.ka.dɑ̃s/plural: décadences
decadence (state of moral or artistic decline or deterioration); decline, decay (deterioration of condition)
Borrowed from Medieval Latin or Late Latin decadentia, from decadēns, present participle of decadō (whence the verb déchoir), from de- + cadō (“to fall”). Doublet of déchéance, naturally inherited from the same Latin root.