terribly

Etymology

From terrible + -ly.

adv

1. (literary or dated) So as to cause terror or awe.
   The lion roared terribly.
   The mere sensuous impact of trumpet or saxophone, whatever it happened to be playing, was an echo, even though a faint echo, of that excitement and abandon. He wanted to taste, smell, hear: his senses were terribly alive. 1959, Anthony Burgess, Beds in the East (The Malayan Trilogy), published 1972, page 519
2. Very; extremely.
   He's terribly busy and you really shouldn't bother him.
   The parsnip, stilton and chestnut combination may taste good, but it's not terribly decorative. In fact, dull's the word, a lingering adjectival ghost of nut roasts past that I'm keen to banish from the table. December 15, 2011, Felicity Cloake, “How to cook the perfect nut roast”, in Guardian
3. Very badly.
   She took part in the karaoke, but sang terribly.