TERRIBLY
terribly, awfully, awful, frightfully
(adverb) used as intensifiers; “terribly interesting”; “I’m awful sorry”
terribly, atrociously, awfully, abominably, abysmally, rottenly
(adverb) in a terrible manner; “she sings terribly”
Source: WordNet® 3.1
Etymology
Adverb
terribly (comparative more terribly, superlative most terribly)
(literary or dated) So as to cause terror or awe.
Very; extremely.
Very badly.
Usage notes
• Adjectives to which "terribly" is often applied: wrong, sorry, important, difficult, hard, afraid, sad, bad, expensive, long, upset, exciting, fast, excited, slow, cold, hot, busy, concerned, pleased, interesting, painful, funny, lonely, ill, good, tired, strong, confused, serious, fond, old, angry, anxious, effective, depressed, familiar, attractive, happy, poor, hungry, sick, big, nice, small, dull, clever, dirty, proud, disappointing, sweet, original, ashamed, efficient, successful, jealous, simple, strange, cruel.
Synonyms
• (causing terror or awe): grisly (obsolete)
• (very): very, extremely, awfully, horribly
Source: Wiktionary
TERRIBLE
Ter"ri*ble, a. Etym: [F., fr. L. terribilis, fr. terrere to frighten.
See Terror.]
1. Adapted or likely to excite terror, awe, or dread; dreadful;
formidable.
Prudent in peace, and terrible in war. Prior.
Thou shalt not be affrighted at them; for the Lord thy God is among
you, a mighty God and terrible. Deut. vii. 21.
2. Excessive; extreme; severe. [Colloq.]
The terrible coldness of the season. Clarendon.
Syn.
– Terrific; fearful; frightful; formidable; dreadful; horrible;
shocking; awful.
– Ter"ri*ble*ness, n.
– Ter"ri*bly, adv.
Source: Webster’s Unabridged Dictionary 1913 Edition