ter‧ri‧bly S2 / terəbli, terɪbli / 副词

1 [ + 形容词 / 副词 ] especially British English very 同义词 extremely :

I’m terribly sorry to have kept you waiting.

The coach was not terribly worried about his team’s poor performance.

2 very badly 同义词 severely :

The little boy missed his mother terribly.