not seen; unperceived; unobserved; invisible.

recognized or comprehended without prior study, as a written text or musical score.

adjective

open , seen , visible

adjective

concealed , curtained , dark , imaginary , imagined , impalpable , impenetrable , imperceptible , inconspicuous , invisible , lurking , not in sight , obscure , occult , out of sight , shrouded , undetected , undiscovered , unnoticed , unobserved , unobtrusive , unperceived , unsuspected , veiled , clandestine , furtive , hidden , secret , surreptitious , underhand