[IBM, probably from slang belly up] Yet another synonym for "broken" or "down". USually connotes a major failure. A system (hardware or software) which is "down" may be already being restarted before the failure is noticed, whereas one which is "casters up" is USually a good excUSe to take the rest of the day off (as long as you' re not responsible for fixing it). [Jargon File]