:macro: /mak'roh/ [techspeak] n. A name (possibly followed by a
formal {arg} list) that is equated to a text or symbolic
expression to which it is to be expanded (possibly with the
substitution of actual arguments) by a macro expander. This
definition can be found in any technical dictionary; what those
won't tell you is how the hackish connotations of the term have
changed over time.
The term `macro' originated in early assemblers, which encouraged the use of macros as a structuring and information-hiding device. During the early 1970s, macro assemblers became ubiquitous, and sometimes quite as powerful and expensive as {HLL}s, only to fall from favor as improving compiler technology marginalized assembler programming (see {languages of choice}). Nowadays the term is most often used in connection with the C preprocessor, LISP, or one of several special-purpose languages built around a macro-expansion facility (such as TeX or UNIX's [nt]roff suite).
Indeed, the meaning has drifted enough that the collective `macros' is now sometimes used for code in any special-purpose application control language (whether or not the language is actually translated by text expansion), and for macro-like entities such as the `keyboard macros' supported in some text editors (and PC TSR or Macintosh INIT/CDEV keyboard enhancers).
:macro-: pref. Large. Opposite of {micro-}. In the mainstream and among other technical cultures (for example, medical people) this competes with the prefix {mega-}, but hackers tend to restrict the latter to quantification.
:macrology: /mak-rol'*-jee/ n. 1. Set of usually complex or crufty macros, e.g., as part of a large system written in {LISP}, {TECO}, or (less commonly) assembler. 2. The art and science involved in comprehending a macrology in sense 1. Sometimes studying the macrology of a system is not unlike archeology, ecology, or {theology}, hence the sound-alike construction. See also {boxology}.
:macrotape: /ma'kroh-tayp/ n. An industry-standard reel of tape, as
opposed to a {microtape}.
:maggotbox: /mag'*t-boks/ n. See {Macintrash}. This is even
more derogatory.
:magic: adj. 1. As yet unexplained, or too complicated to explain; compare {automagically} and (Arthur C.) Clarke's Third Law: "Any sufficiently advanced technology is indistinguishable from magic." "TTY echoing is controlled by a large number of magic bits." "This routine magically computes the parity of an 8-bit byte in three instructions." 2. Characteristic of something that works although no one really understands why (this is especially called {black magic}). 3. [Stanford] A feature not generally publicized that allows something otherwise impossible, or a feature formerly in that category but now unveiled. Compare {black magic}, {wizardly}, {deep magic}, {heavy wizardry}.
For more about hackish `magic', see {A Story About `Magic'} (in {appendix A}).
:magic cookie: [UNIX] n. 1. Something passed between routines or programs that enables the receiver to perform some operation; a capability ticket or opaque identifier. Especially used of small data objects that contain data encoded in a strange or intrinsically machine-dependent way. E.g., on non-UNIX OSes with a non-byte-stream model of files, the result of `ftell(3)' may be a magic cookie rather than a byte offset; it can be passed to `fseek(3)', but not operated on in any meaningful way. The phrase `it hands you a magic cookie' means it returns a result whose contents are not defined but which can be passed back to the same or some other program later. 2. An in-band code for changing graphic rendition (e.g., inverse video or underlining) or performing other control functions. Some older terminals would leave a blank on the screen corresponding to mode-change magic cookies; this was also called a {glitch}. See also {cookie}.