untellable vs ineffable

untellable and ineffable both are adjectives.

Word	Noun	Adjective	Verb	Adverb
untellable	No	Yes	No	No
ineffable	No	Yes	No	No

As adjectives, untellable and ineffable are synonyms defined as:

Other synonyms of untellable include indefinable, indescribable, unspeakable, unutterable.

untellable (adjective)	ineffable (adjective)
defying expression or description	defying expression or description
	too sacred to be uttered