Adjective
Not using electricity from the public electrical supply system.
Not reachable via a publicly available communication system, such as the Internet or a mobile telephone network.
Isolated; in a remote location; in seclusion; not participating in some official process or system.
Adverb
In or into a situation or place in which electricity from the public electricity system is not used.
In or into a clandestine or isolated situation or place, especially one in which public communication is curtailed.
Secretly; in a clandestine manner.