that has existed for longer than people can remember 古老的;远古的;无法追忆的 an immemorial tradition 古老的传统 My family has lived in this area from time immemorial (= for a very long time). 我的家族在这个地区已经生活了不知有多少年了。
Word Originearly 17th cent.: from medieval Latin immemorialis, from in- ‘not’ + memorialis ‘relating to the memory’.