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; unconnected ] on-line
Syn. -- offline, off line(predicate). [ WordNet 1.5 ]

2. Hence: (fig.) Outside of or after a meeting or formal discussion; as, we can discuss the details off-line; -- a term used at meetings and conferences to suggest postponing detailed discussion of a topic so as not to occupy the time of a large group most of whom may not be interested. [ PJC ]