Not accessible; not to be reached, obtained, or approached; as, an inaccessible rock, fortress, document, prince, etc.

capable of being reached only with great difficulty or not at all

not capable of being obtained; "a rare work, today almost inaccessible"; "timber is virtually unobtainable in the islands"; "untouchable resources buried deep within the earth"

In XOM, said of an object for which the client does not possess a valid designator or handle.

See accessible.