1. What sysadmins have to do to correct sudden operational problems.
An opposite of hacking.
"Been hacking your new newsreader?"
"No, a power glitch hosed the network and I spent the whole afternoon fighting fires."
2. The act of throwing lots of manpower and late nights at a project, especially to get it out before deadline.
See also gang bang
, Mongolian Hordes technique
; however, the term "firefighting" connotes that the effort is going into chasing bugs rather than adding features.