IPA: /ˈdɛkədəns/
KK: /dɛkəˌdɛnsi/
A state of decline or decay, often associated with excessive indulgence in pleasure or luxury.
The city's decadency was evident in its crumbling buildings and lavish parties.
Decadency is formed from "de-" (meaning down or away) and "cadere" (meaning to fall). The term describes a state of decline or falling away from a previous state of excellence or morality.
Think of 'falling down' ('de-') from a higher state ('cadere') to remember that decadency refers to a decline in quality or morality.