Ineffable (adjective)

1. Too great or extreme to be described in words.
2. Too sacred or too great for words; unspeakable; indescribable.

Origin:

From latin ineffabilis, from in- + effabilis ("that can be expresse.d")

Examples:

1. The beauty of the sunset was ineffable.
2. The feeling of love is ineffable.
3. The ineffable mystery of existence.
4. The ineffable joy of the moment.
5. The ineffable awe of the grand canyon.