This is the 5751st most frequent Japanese word.
とっくに
Already; long ago; long since.
The word 'とっくに' is used to emphasize that the event has concluded a considerably long time ago.
そのイベントはとっくに終わった。
That event ended a long time ago.
Here, 'とっくに' denotes a significant passage of time since the action occurred, emphasizing how long ago.
とっくに彼女は帰宅したと思う。
I think she went home quite a while ago.
In this sentence, 'とっくに' expresses that the feeling of boredom developed a notably long time ago.