From The Free On-line Dictionary of Computing: (http://www.foldoc.org/, Editor Denis Howe)
1. An undigested and voluminous mass of information about a problem or the state of a system, especially one routed to the slowest available output device (compare core dump), and most especially one consisting of hexadecimal or octalrunes describing the byte-by-byte state of memory, mass storage, or some file. In elder days, debugging was generally done by "groveling over" a dump (see grovel); increasing use of high-level languages and interactive debuggers has made such tedium uncommon, and the term "dump" now has a faintly archaic flavour.
2. A backup. This usage is typical only at large time-sharing installations.
