Unnameable (adjective)

1. Too terrible or shocking to be described or referred to by name.
2. Too elusive or intangible to be named or identified.
3. Beyond the limits of language or description.

Origin:

Early 17th century, from un- + nameable.

Examples:

1. The unnameable horror was beyond human comprehension.
2. The unnameable pain was felt deep in the soul.
3. The unnameable feeling was a mixture of fear and awe.
4. The unnameable experience was indescribable.
5. The unnameable truth was shrouded in mystery.