Too great or extreme to be expressed or described in words — incapable of being spoken or put into language.

From the Latin ineffabilis, from in (not) and effabilis (speakable), derived from effari, to speak out — that which cannot be spoken.

Used in theology to describe divine attributes that transcend human comprehension — the ineffability of God is a core concept in apophatic or negative theology.

In contemporary usage often applied to profound aesthetic experience — the feeling that a piece of music or a landscape exceeds any verbal description.

Originally a legal term in Roman law meaning unutterable in court — certain categories of evidence were considered ineffable and could not be introduced in testimony.