continuing for a very long time; happening again and again 长久的；持续的；反复出现的 the perennial problem of water shortage 缺水这个老问题 that perennial favourite, hamburgers 汉堡包，永远受人喜爱的食品 Colonialism in different forms is a perennial theme of history. 不同形式的殖民主义是历史的永恒主题。
(of plants 植物 living for two years or more 多年生的
Word Originmid 17th cent. (in the sense ‘remaining leafy throughout the year, evergreen’): from Latin perennis ‘lasting the year through’ + -ial.