| nonleaking(adjective, tight, proof, impervious, hermetic) |
| obscure(dark, secret, unknown, isolated, hidden) |
| occult(noun, obscure, dark, secret, unknown) |
| out of view(expression, adjective, idiom, obscure, dark) |
| pressureproof(adjective, tight, proof, impervious, hermetic) |
| pressurised(adjective, tight, proof, impervious, hermetic) |
| pressurized(adjective, tight, proof, impervious, hermetic) |
| private(secret, unknown, isolated, hidden, concealed) |
| proof(adjective, tight, impervious, hermetic) |
| reclusive(adjective, isolated, uncompanionable) |
| recondite(adjective, obscure, dark, secret, unknown) |
| retentive(adjective, tight, proof, impervious, hermetic) |
| screened(obscure, dark, secret, unknown, hidden) |
| sealed-in(adjective, tight, proof, impervious, hermetic) |
| secluded(adjective, obscure, dark, secret, unknown) |
| sequestered(obscure, dark, secret, unknown, hidden) |
| shadowy(obscure, dark, secret, unknown, hidden) |
| shrouded(adjective, secret, unknown, isolated, hidden) |
| tightly sealed(adjective, tight, proof, impervious, hermetic) |
| totally enclosed(adjective, tight, proof, impervious, hermetic) |