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M 1. Abbreviation of prefix MEGA-. 2. Symbol for
MUTUAL INDUCTANCE. 3. Symbol for MODI-
FIED INDEX OF REFRACTION.
m 1. Abbreviation of prefix MILLI-. 2. Symbol for
MASS. 3. Abbreviation of METER. 4. Abbreviation
of MILE. (Also, mi.) 5. Symbol for MODULA-
TION COEFFICIENT.
m 2 Abbreviation of square meter, the SI unit of
area.
m 3 Abbreviation of cubic meter, the SI unit of volume.
MA 1. Abbreviation of MAGNETIC AMPLIFIER.
(Also, magamp.) 2. Abbreviation of MEGAMPERE.
mA Abbreviation of MILLIAMPERE.
Mache unit A unit of radioactivity equivalent to
13.47 disintegrations per second (3.64 × 10 –10
curie) per liter. It represents the concentration of
radon gas per liter (when all radiation is absorbed)
that will result in a saturation current of
10 –3 esu (not to be confused with MACH NUM-
BER).
machine address See ABSOLUTE ADDRESS.
machine code See MACHINE LANGUAGE.
machine cycle In a machine whose operation is
periodic, a complete sequence constituting a period
of operation.
machine error In a computer or data-processing
system, an error attributable to a hardware failure,
rather than to a software fault.
machine instruction A computer program instruction
written in MACHINE LANGUAGE.
machine knowledge General term for data stored
in an artificially intelligent computer system, and
the ability of the computer to use that data in
meaningful ways.
machine language Computer program instructions
and data represented in binary form. In the
hierarchy of programming languages, it is the
lowest; the computer works directly with it. All
high-level languages are translated to machine
language by an assembler, compiler, interpreter,
or monitor system.
machine learning In artificial intelligence, a computer’s
ability to learn through repeated calculations
for particular problems.
machine logic 1. The way that a computer’s functional
parts are interrelated. 2. The facility
whereby a computer solves problems.
machine operation The performance by a computer
of a built-in function (e.g., subtraction).
machine operator A person participating in implementing
and overseeing the processing of computer
programs.
machine word In computer operations, the address
of a memory location composed of the full
number of bits normally handled by each register
of the machine.
machining In industrial robotics, the mechanical
modification of parts during assembly. Examples:
drilling, welding, sanding, polishing, and painting.
Mach number For a medium such as air, the ratio
of the speed of a body in motion to the speed of
sound in the medium. (Not to be confused with
MACHE UNIT.)
macro 1. A control shortcut, in which a function
requiring the actuation of several switches is abbreviated,
via a microcomputer, so that it can be
executed by actuating only one or two switches.
2. Abbreviation of MACROINSTRUCTION.
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