A computer server that will not function properly -- usually manifested by repeatedly crashing or rebooting itself. This can reference both hardware and software. Often used to refer to notoriously unreliable programs or devices even if they are not currently "swerving".
Common causes of "swerving" are malfunctioning hardware (bad capacitors are notorious for causing unexplained reboots) and poorly written or corrupted software.
I've been working on this swerver for over a week and I still can't make it keep an uptime of more than three hours. They need to re-check the hardware.
I convinced them to let me convert the box from Windows Swerver 2003 over to Ubuntu. Now maybe I can have a weekend without getting called because it crashed!