Concealed from view
secreted, secluded, out of sight, private, covert, concealed, undercover, occult, arcane, in the dark, in a haze, in a fog, in darkness, masked, screened, veiled, cloaked, obscured, disguised, socked in, invisible, clouded, sealed, unobserved, blotted, in eclipse, impenetrable, unseen, eclipsed, unexposed, camouflaged, enshrouded, undetected, shrouded, shadowy, unknown, indiscernible, latent, buried, opaque, deep, unsuspected, inscrutable, unapparent, inexplicable, illegible, unintelligible, imperceptible, puzzling, unobserved, out of view, dim, recondite, overlaid, clandestine, subterranean, cloistered, suppressed, secured, hermetic, dark, inward, underground, unrevealed, undisclosed, imperceivable, inert, withheld, surreptitious, sequestered, underhand, unsearchable, kept in the dark*, under wraps*, kept dark*; see also covered 1, isolated, obscure 1, withdrawn.
Antonyms obvious*, open, apparent.