decadence (n.) Look up decadence at Dictionary.com
1540s, from Middle French décadence (early 15c.), from Medieval Latin decadentia "decay," from decadentem (nominative decadens) "decaying," present participle of decadere "to decay," from Latin de- "apart, down" (see de-) + cadere "to fall," from PIE root *kad- "to lay out, fall or make fall" (see case (n.1)). Used of periods in art since 1852, on French model.