unspeakable vs terrible

unspeakable and terrible both are adjectives.

Word	Noun	Adjective	Verb	Adverb
unspeakable	No	Yes	No	No
terrible	No	Yes	No	No

As adjectives, unspeakable and terrible are synonyms defined as:

Other synonyms of unspeakable include abominable, atrocious, awful, dreadful, painful.

unspeakable (adjective)	terrible (adjective)
exceptionally bad or displeasing	causing fear or dread or terror
defying expression or description	extreme in degree or extent or amount or impact
too sacred to be uttered	intensely or extremely bad or unpleasant in degree or quality
	exceptionally bad or displeasing