ineffably vs indescribably

ineffably and indescribably both are adverbs.

Word	Noun	Adjective	Verb	Adverb
ineffably	No	No	No	Yes
indescribably	No	No	No	Yes

As adverbs, ineffably and indescribably are synonyms defined as:

Other synonyms of ineffably include inexpressibly, unspeakably, unutterably.

ineffably (adverb)	indescribably (adverb)
to an inexpressible degree	to an inexpressible degree