Synonyms:
- arcane,
- bated,
- blurred,
- breathy,
- cabalistic,
- censored,
- choked,
- choking,
- classified,
- close,
- closed,
- concealed,
- croaking,
- crushed,
- cryptic,
- damped,
- dampened,
- dark,
- dead,
- deadened,
- drawling,
- drawly,
- dull,
- dulled,
- dysphonic,
- enigmatic,
- esoteric,
- flat,
- guttural,
- harsh,
- hawking,
- hermetic,
- hidden,
- hoarse,
- hush-hush,
- inarticulate,
- indistinct,
- latent,
- lisping,
- mispronounced,
- muffled,
- muted,
- muzzy,
- mysterious,
- nasal,
- occult,
- quashed,
- quavering,
- quelled,
- repressed,
- restricted,
- secret,
- shaking,
- shaky,
- smashed,
- smothered,
- snuffling,
- softened,
- sordo,
- squashed,
- squelched,
- strangled,
- subdued,
- suffocated,
- suppressed,
- thick,
- throaty,
- top secret,
- tremulous,
- twangy,
- ulterior,
- unbreatheable,
- under security,
- under wraps,
- undisclosable,
- undisclosed,
- undivulgable,
- undivulged,
- unrevealable,
- unrevealed,
- unspoken,
- untellable,
- untold,
- unutterable,
- unuttered,
- unwhisperable,
- velar