Synonyms of the word

frightfully

• adv. In a frightful manner.
• adv. Very, extremely.

awful

• adj. Oppressing with fear or horror; appalling, terrible.
• adj. (now rare) Inspiring awe; filling with profound reverence or respect; profoundly impressive.
• adj. Struck or filled with awe.
• adj. (obsolete) Terror-stricken.
• adj. Worshipful; reverential; law-abiding.
• adj. Exceedingly great; usually applied intensively.
• adj. Very bad.
• adv. (colloquial, US, Canada) Very, extremely.

awfully

• adv. Badly, terribly.
• adv. (not comparable) Very; exceedingly; extremely; excessively.
• adv. (archaic) In a manner inspiring awe.
• adv. (archaic) Reverently.
• adv. (obsolete) Fearfully.

terribly

• adv. (literary or dated) Causing terror or awe.
• adv. Very; extremely.
• adv. Very badly.