Synonyms:
- arcane,
- awesome,
- awful,
- cabalistic,
- censored,
- classified,
- close,
- closed,
- concealed,
- cryptic,
- dark,
- divine,
- enigmatic,
- esoteric,
- heavenly,
- hermetic,
- hidden,
- holy,
- hush-hush,
- incommunicable,
- inconceivable,
- incredible,
- indefinable,
- indescribable,
- ineffable,
- inenarrable,
- inexpressible,
- innominable,
- inviolable,
- inviolate,
- latent,
- marvelous,
- mysterious,
- noncommunicable,
- numinous,
- occult,
- prodigious,
- religious,
- restricted,
- sacred,
- sacrosanct,
- secret,
- smothered,
- spiritual,
- stifled,
- suppressed,
- top secret,
- ulterior,
- unbelievable,
- unbreatheable,
- undefinable,
- under security,
- under wraps,
- undisclosable,
- undisclosed,
- undivulgable,
- undivulged,
- unimaginable,
- unmentionable,
- unnameable,
- unrevealable,
- unrevealed,
- unspeakable,
- unspoken,
- untellable,
- untold,
- untouchable,
- unuttered,
- unwhisperable,
- venerable,
- wonderful,
- wondrous