M contour: A line on a Nyquist diagram connecting points having the same magnitude of the primary feedback ratio.
M meter: A class of instruments which measure the liquid water content of the atmosphere.
M synchronization: A linking arrangement between a camera lens and the flashbulb unit to allow a 15-millisecond delay of the shutter so that the bulb burns to its brightest point before the shutter opens.
M-A-N scavenging system: A system for removing used oil and waste gases from a cylinder of an internal combustion engine in which the exhaust ports are located above the intake ports on the same side of the cylinder, so that gases circulate in a loop, leaving a dead spot in the c
M-design bit: A long-shank, box-threaded core bit made to fit M-design core barrels.
M-design core barrel: A double-tube core barrel in which a 2½°-taper core lifter is carried inside a short tubular sleeve coupled to the bottom end of the inner tube, and the sleeve extends downward inside the bit shank to within a very short distance behind the face of the co
macadam: Uniformly graded stones consolidated by rolling to form a road surface, may be bound with water or cement, or coated with tar or bitumen.
maceration: The process of extracting fragrant oils from flower petals by immersing them in hot molten fat.
macroanalytical balance: A relatively large type of analytical balance that can weigh loads of up to 200 grams to the nearest 0.1 milligram.
macroelement: An element of a work cycle whose time span is long enough to be observed and measured with a stopwatch.
macrorheology: A branch of rheology in which materials are treated as homogeneous or quasi-homogeneous, and processes are treated as isothermal.
macroscopic anisotropy: Phenomenon in electrical downhole logging wherein electric current flows more easily along sedimentary strata beds than perpendicular to them.