noun, noun or participle which takes 'suru', intransitive verb
decline and fall; ruin; collapse
Refers to the process of weakening and eventual downfall, often of nations, civilizations, or institutions. Somewhat formal and literary.
その帝国は内乱によって衰亡した。
The empire declined and fell due to civil war.
歴史
Historians study the causes of the decline and fall of civilizations.