from/since time immemorial literary for a very long time从很早开始,自古以来
Her family had farmed that land since time immemorial.她的家族从很早开始便在那块土地上耕耘了。
formal existing or traditional for an extremely long time年代久远的,古老的
She said it was the immemorial custom of the villagers to have a feast after the harvesting.她说村民们在收割之后举行宴会是一个古老的风俗。