The origin of the "core dump" originated from magnetic core memory. It's an electro-mechanical form of memory which retained it's settings even after power has been removed.
If a program were to crash the system, you could remove the memory core and physically examine what state the machine is in when it crashed.
This method is no longer in use, since the common use of RAM such as DRAM, SDRAM, and other memory types which lose their settings when power is removed.
For most non-developers, a core dump is simply a large, waste of space on your hard drive, when GIMP craps out on a linux or unix system.