I . a.
1.
Hidden, hid, concealed, covert, privy, close, covered, shrouded, veiled, unseen, unknown, unrevealed, mysterious, cryptic.
2.
Clandestine, sly, underhand, underhanded, concealed, hidden, privy, stealthy.
3.
Secluded, retired, private, unseen, hid, concealed, privy.
4.
Occult, mysterious, latent, obscure, recondite, abstruse, unknown, hidden.
II . n.
1.
Something concealed.
2.
Mystery.