形容詞 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這個(gè)村子里。
2. From time immemorial the tribe have buried their dead here.
   自古以來該部落就把死者埋葬在這里。
3. Members of my family have lived in this house since time immemorial.
   我的家人很久以前就住在這幢房子里了。
4. The museum has many immemorial cultural relics.
   該博物館收藏了很多極其古老的文物。

im.me.mo.ri.al

adj.（形容詞）
Reaching beyond the limits of memory, tradition, or recorded history.
古老的，久遠(yuǎn)的：超越記憶、傳統(tǒng)或歷史記錄的限度的

來源：
Medieval Latin immemori3lis
中世紀(jì)拉丁語 immemori3lis
Latin in- [not] * see in-
拉丁語 in- [不] *參見 in-
Latin memori3lis [memorial] * see memorial
拉丁語 memori3lis [記憶的] *參見 memorial

【引伸】
im.memo.rially
adv.（副詞）