Immemorial

прилагательное давний, незапамятный, древний, старый Синоним(ы): ancient

Большой англо-русский словарь

Immemorial

adjective Etymology: probably from French immémorial, from Middle French, from Medieval Latin immemorialis lacking memory, from Latin in- + memorialis memorial extending or existing since beyond the reach of memory, record, or tradition Example: existing from time immemorialimmemorially adverb

Merriam-Webster's Collegiate Dictionary