EMACS /ee'maks/ n.
[from Editing MACroS] The ne plus ultra of hacker editors, a programmable text editor with an entire LISP system inside it. It was originally written by Richard Stallman in TECO under ITS at the MIT AI lab; AI Memo 554 described it as "an advanced, self-documenting, customizable, extensible real-time display editor". It has since been reimplemented any number of times, by various hackers, and versions exist that run under most major operating systems. Perhaps the most widely used version, also written by Stallman and now called "GNU EMACS" or GNUMACS, runs principally under Unix. (Its close relative XEmacs is the second most popular version.) It includes facilities to run compilation subprocesses and send and receive mail or news; many hackers spend up to 80% of their tube time inside it. Other variants include GOSMACS, CCA EMACS, UniPress EMACS, Montgomery EMACS, jove, epsilon, and MicroEMACS. (Though we use the original all-caps spelling here, it is nowadays very commonly `Emacs'.)
Some EMACS versions running under window managers iconify as an
overflowing kitchen sink, perhaps to suggest the one feature the
editor does not (yet) include. Indeed, some hackers find EMACS too
heavyweight and baroque for their taste, and expand the
name as `Escape Meta Alt Control Shift' to spoof its heavy reliance
on keystrokes decorated with bucky bits. Other spoof
expansions include `Eight Megabytes And Constantly Swapping' (from
when that was a lot of core), `Eventually
Computer Storage', and `EMACS Makes A Computer Slow' (see
recursive acronym). See also vi.