THESAURUS
hermetic
abstruse, airtight, arcane, ballproof, bombproof, bulletproof, burglarproof, cabalistic, censored, classified, cloistered, close, closed, compact, concealed, corrosionproof, cryptic, dampproof, dark, deep, dustproof, dusttight, enigmatic, esoteric, fast, fire-resisting, fireproof, firm, flameproof, foolproof, gasproof, gastight, heavy, hermetical, hermetically sealed, hidden, holeproof, hush-hush, impervious, impervious to, latent, leakproof, lightproof, lighttight, mysterious, noiseproof, occult, oilproof, oiltight, profound, proof, proof against, punctureproof, rainproof, raintight, recluse, resistant, restricted, rustproof, sealed, secluse, seclusive, secret, sequestered, shatterproof, shellproof, shut fast, smokeproof, smoketight, smothered, snug, soundproof, staunch, stifled, stormproof, stormtight, suppressed, tight, top secret, ulterior, unbreatheable, under security, under wraps, undisclosable, undisclosed, undivulgable, undivulged, unrevealable, unrevealed, unspoken, untellable, untold, unutterable, unuttered, unwhisperable, water-repellant, waterproof, watertight, weatherproof, windproof, windtight