You use perennial to describe situations or states that keep occurring or which seem to exist all the time; used especially to describe problems or difficulties.
例句
...the perennial urban problems of drugs and homelessness...毒品和無家可歸這兩個一直困擾城市的問題There's a perennial shortage of teachers with science qualifications.有理科教學資格的老師一直都很短缺。
ADJ
（植物）多年生的
A perennial plant lives for several years and has flowers each year.
例句
...a perennial herb with greenish-yellow flowers.開綠黃色花的多年生香草
英英詞典釋義
Adverb
1. in a perennial manner; repeatedly;
"We want to know what is perennially new about the world"