Immemorial (adjective)
immemorial [ im-uh-mawr-ee-uhl, -mohr- ]

adjective
1. extending back beyond memory, record, or knowledge: from time immemorial.

OTHER WORDS FROM IMMEMORIAL
im·me·mo·ri·al·ly, adverb

WORDS RELATED TO IMMEMORIAL
archaic, fixed, forever, long-standing, prehistoric, primeval, rooted, time-honored, traditional, age-old, olden

SYNONYMS FOR IMMEMORIAL
See more synonyms on Thesaurus.com
timeless, ancient, ageless, olden.

Origin: From the Medieval Latin word immemoriālis, dating back to 1595–1605. See im-, memorial

EXAMPLE SENTENCES FROM THE WEB FOR IMMEMORIAL
As Larkin would no doubt expect, the history of dubious royal parenting steps back to time immemorial.
KATE AND WILLIAM’S ROYAL FAMILY VALUES|TOM SYKES|SEPTEMBER 22, 2014|DAILY BEAST

Ah yes, the threat wielded against the deliberately childless since time immemorial: Conform or you will regret it!
POPE FRANCIS IS WRONG ABOUT MY CHILD-FREE LIFE|AMANDA MARCOTTE|JUNE 6, 2014|DAILY BEAST

Know that the world honors in and through you the builders of a country that is both immemorial and fragile, always under threat.
BERNARD-HENRI LÉVY: ANDRÉ MALRAUX’S BANGLADESH, BEFORE THE RADICALS|BERNARD-HENRI LÉVY|APRIL 28, 2014|DAILY BEAST

These are the same tactics that management has used since time immemorial.
IT’S TIME TO RIP THE MONEY OUT OF THE NCAA|ROBERT SILVERMAN|APRIL 1, 2014|DAILY BEAST

Now YOU come up with a sentence (or fic? or graphic?) that best illustrates the word.