It means inexplicable, which can't be explained in words. Unspeakable, you can't express it. Unspeakable, indescribable, unspeakable, unpronounced, sublime, wonderful.
Ineffable: adj. 1 - applies to what cannot be expressed with words: inexpressible joy. 2. is it said that cannot be explained with words for being extraordinary and grandiose or be very subtle or diffuse.
Adjective. Not expressible ( 41 words;. Compound - Latin - the custodial inseparable preposition ( negative ) 'in' and the verb «effari» ( of «ecfari»: pronounce «EC»: outside, and 'do': talk ): Express. Synonyms: unspeakable, unspeakable, unspeakable, inexpressible.