adj. 25B6; adjective
a hidden camera : CONCEALED, secret, invisible, unseen, out of sight; camouflaged, disguised, masked.
a hidden meaning : OBSCURE, unclear, concealed, indistinct, indefinite, vague, unfathomable, inexplicable; cryptic, mysterious, secret, covert, abstruse, arcane; ulterior, deep, subliminal, coded.
visible, obvious.