/at'par-tee/ (Or "@-sign party") An antiquated term for a gathering of hackers at a science-fiction convention (especially the annual Worldcon) to which only people who had an electronic mail address were admitted. The term refers to the commercial at symbol, "@", in an e-mail address and dates back to the era when having an e-mail address was a distinguishing characteristic of the select few who worked with computers. Compare boink.

Free Online Dictionary of Computing