offline

from The Collaborative International Dictionary of English v.0.48

off-line \off-line\ adj.
   1. (Computers) Not connected; -- of computers or computer
      peripherals normally connected or intended to be connected
      to other computers by a communications line; as, we can't
      print the document because the printer is off-line.
      [Narrower terms: {disconnected, not ready, off};

from Jargon File (4.4.4, 14 Aug 2003)

offline
 adv.

   Not now or not here. "Let's take this discussion offline."
   Specifically used on {Usenet} to suggest that a discussion be moved
   off a public newsgroup to email.