inconceivable vs unimaginable

inconceivable and unimaginable both are adjectives.

Word	Noun	Adjective	Verb	Adverb
inconceivable	No	Yes	No	No
unimaginable	No	Yes	No	No

As adjectives, inconceivable and unimaginable are synonyms defined as:

Other synonyms of inconceivable include impossible, out of the question.

inconceivable (adjective)	unimaginable (adjective)
totally unlikely	totally unlikely