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 hex or octal runes 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 flavor.
2. A backup. This usage is typical only at large timesharing installations.