terribly, extremely
Mira, estoy terriblemente ocupado.
Look, I’m terribly busy.
I'm terribly tired.
Yo sentí a la casa sacudirse terriblemente.
I felt the house shake terribly.
Jane es una chica terriblemente atractiva.
Jane is a terribly attractive girl.
La fiesta fue terriblemente aburrida.
The party was terribly boring.