► 動詞衰退  [すいたい]  [
衰退する]    
meaning:  decline  rank: 3☆ 
帝国は衰退した ⇨ The empire declined  
(☛ Something powerful to decline gradually)► 名詞衰退  [すいたい]    
meaning:  decline  rank: 3☆ 
帝国の衰退 ⇨ The decline of the empire  
(☛ A gradual decline of what used to be powerful)More examples:- 国は衰退の一途を辿った ⇨ The country followed one way road of decline, kept declining