1. <data, architecture> A computer architecture in which, within a given multi-byte numeric representation, the most significant byte has the lowest address (the word is stored "big-end-first").
Most processors, including the IBM 370 family, the PDP-10, the Motorola microprocessor families, and most of the various RISC designs current in mid-1993, are big-endian.
2. <networking, standard> A backward electronic mail address. The world now follows the Internet hostname standard (see FQDN) and writes e-mail addresses starting with the name of the computer and ending up with the country code (e.g. email@example.com). In the United Kingdom the Joint Networking Team decided to do it the other way round (e.g. firstname.lastname@example.org) before the Internet domain standard was established. Most gateway sites required ad-hockery in their mailers to handle this.
By July 1994 this parochial idiosyncracy was on the way out and mailers started to reject big-endian addresses. By about 1996, people would look at you strangely if you suggested such a bizarre thing might ever have existed.