衰退
Common
Noun
Irregular
Intransitive
1
noun (common) (futsuumeishi)noun or participle which takes the aux. verb suruintransitive verb
decline;degeneration;decay;waning;ebbing
４７５年はローマ帝国の「衰退」を示す年ではあっても、「滅亡」を意味する年ではありません。
Although 475AD is the year that shows the 'decline' of the Roman Empire, it is not the year of its 'fall'.
Other forms
衰頽 【すいたい】 (rarely used kanji form)