| unseen(adjective, hidden, covert, stealthy, unnoticed) |
| undiscovered(adjective, knowledge, obscure, hidden, imaginary) |
| unexposed(adjective, knowledge, obscure, dark, unknown) |
| invisible(adjective, obscure, dark, secret, unknown) |
| obscure(adjective, dark, secret, unknown, hidden) |
| hidden(adjective, secret, unseen) |
| unobserved |
| unperceived(adjective, covert, stealthy, unnoticed) |
| undisclosed(obscure, dark, secret, unknown, hidden) |
| unexplored(adjective, unfound) |
| unfound(adjective, knowledge, obscure, undiscovered, untraveled) |
| unknown(adjective, obscure, dark, secret, hidden) |
| unrevealed(obscure, dark, secret, unknown, hidden) |
| unnoticed |
| abstruse(obscure, dark, secret, unknown, hidden) |
| close(obscure, dark, secret, unknown, hidden) |
| clouded(obscure, dark, secret, unknown, hidden) |
| cryptic(adjective, obscure, dark, secret, unknown) |
| eclipsed(obscure, dark, secret, unknown, hidden) |
| esoteric(obscure, dark, secret, unknown, hidden) |