difficult to find; "hidden valleys"; "a hidden cave"; "an obscure retreat" 同义词:obscure,
designed to elude detection; "a hidden room or place of concealment such as a priest hole"; "a secret passage"; "the secret compartment in the desk" 同义词:secret,
not accessible to view; "concealed (or hidden) damage"; "in stormy weather the stars are out of sight" 同义词:concealed, out of sight,