a. 太古的, 远古的, 无法追忆的

[法] 无法追溯的, 无法记忆的, 太古的

[ adj ]
long past; beyond the limits of memory or tradition or recorded history
<adj.all>
time immemorial

Immemorial \Im`me*mo"ri*al\, a. [Pref. im- not + memorial: cf.
F. imm['e]morial.]
Extending beyond the reach of memory, record, or tradition;
indefinitely ancient; as, existing from time immemorial.
``Immemorial elms.'' --Tennyson. ``Immemorial usage or
custom.'' --Sir M. Hale.

{Time immemorial} (Eng. Law.), a time antedating (legal)
history, and beyond ``legal memory'' so called; formerly
an indefinite time, but in 1276 this time was fixed by
statute as the begining of the reign of Richard I. (1189).
Proof of unbroken possession or use of any right since
that date made it unnecessary to establish the original
grant. In 1832 the plan of dating legal memory from a
fixed time was abandoned and the principle substituted
that rights which had been enjoyed for full twenty years
(or as against the crown thirty years) should not be
liable to impeachment merely by proving that they had not
been enjoyed before.