expression, noun
a long time ago; ages ago; long since
Emphasizes that something happened or was completed far in the past, often with a nuance of 'already long ago' or 'way back when'. Used in casual to neutral contexts.
その話はとっくの昔に終わったよ。
That matter was settled ages ago.
彼はとっくの昔に帰りました。
He went home a long time ago.