" immemorial "

[Adjective]  | "im*me*mo*ri*al" | \ ˌi-mə-ˈmȯr-ē-əl \

1: extending or existing since beyond the reach of memory, record, or tradition

Origin: 1602 ;

 Probably from French immémorial, from Middle French, from Medieval Latin immemorialis lacking memory, from Latin in- + memorialis memorial;

[Noun]  | "time immemorial" 

1: time so long past as to be indefinite in history or tradition —called also time out of mind

2: a time antedating a period legally fixed as the basis for a custom or right

Origin: 1593 ;

[Idiom]  | "since time immemorial" 

1: for a very long time

[Adjective]  | "immemorial"