immemorial

形容词 immemorial:

1. long past; beyond the limits of memory or tradition or recorded history

1. My family has lived in this village since time immemorial.
   我家很早以前就一直住在这个村子里。
2. From time immemorial the tribe have buried their dead here.
   自古以来该部落就把死者埋葬在这里。
3. Members of my family have lived in this house since time immemorial.
   我的家人很久以前就住在这幢房子里了。
4. The museum has many immemorial cultural relics.
   该博物馆收藏了很多极其古老的文物。

im.me.mo.ri.al

adj.（形容词）
Reaching beyond the limits of memory, tradition, or recorded history.
古老的，久远的：超越记忆、传统或历史记录的限度的

来源：
Medieval Latin immemori3lis
中世纪拉丁语 immemori3lis
Latin in- [not] * see in-
拉丁语 in- [不] *参见 in-
Latin memori3lis [memorial] * see memorial
拉丁语 memori3lis [记忆的] *参见 memorial

【引伸】
im.memo.rially
adv.（副词）