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Eng ID Term Definition
3201
medium frequency (MF)
See FREQUENCY: RADIO.
3202
medusa
See COELENTERATE and JELLYFISH.
3203
megacycle
One million CYCLES; one thousand KILOCY­CLES. The term is often used incorrectly as the equivalent of one million CYCLES PER SECOND.
3204
megahertz
One million HERTZ; one thousand KILO­HERTZ. The term is used as the equivalent of one million CYCLES PER SECOND.
3205
melting point
Temperature of change from the solid to the liquid phase of a substance. It is a function of pressure.
3206
menu
A list of commands and/or options. The user selects the desired command by moving the CURSOR to the respective position on the menu or by en... more
A list of commands and/or options. The user selects the desired command by moving the CURSOR to the respective position on the menu or by entering an appropriate code at the command entry line of the DISPLAY.
3207
Mercator: transverse
See PROJECTION: TRANSVERSE MERCA­TOR.
3208
Mercator chart
See CHART.
3209
Mercator projection
See PROJECTION.
3210
Mercator sailing
See SAILING.
3211
mercurial (or mercury) barometer
See BAROMETER.
3212
meridian
A north-south reference line, particularly a GREAT CIRCLE through the GEOGRAPHICAL POLES of the EARTH, from which LONGITUDES (or DEPARTURES)... more
A north-south reference line, particularly a GREAT CIRCLE through the GEOGRAPHICAL POLES of the EARTH, from which LONGITUDES (or DEPARTURES) and AZI­MUTHS are reckoned; or a plane normal to the GEOID or SPHEROID defining such a line. The term usually refers to the UPPER BRANCH.
3213
meridian: astronomical
A line on the surface of the EARTH connecting points having the same ASTRONOMICAL LONGITUDE. Because the DEFLECTION OF THE VERTICAL is not t... more
A line on the surface of the EARTH connecting points having the same ASTRONOMICAL LONGITUDE. Because the DEFLECTION OF THE VERTICAL is not the same at all points, an astronomical meridian is an irregular line, not lying in a single plane. Also called terrestrial meridian.
3214
meridian: celestial
A GREAT CIRCLE of the CELESTIAL SPHERE through the CELESTIAL POLES and the ZENITH. The expression usually refers to the UPPER BRANCH.
3215
meridian: central
See MERIDIAN: INITIAL.
3216
meridian: compass
A line through the north-south points of a MAGNETIC COMPASS. The compass card axis lies in the compass meridian.
3217
meridian: geodetic
A line on a SPHEROID which has the same GEODETIC LONGITUDE at every point.
3218
meridian: geographic(al)
A general term, applying alike to an ASTRONOMICAL or a GEODETIC MERIDIAN.
3219
meridian: Greenwich
The ASTRONOMICAL MERIDIAN through the centre of the TRANSIT instrument of the observato­ry of Greenwich, England, serving as the reference f... more
The ASTRONOMICAL MERIDIAN through the centre of the TRANSIT instrument of the observato­ry of Greenwich, England, serving as the reference for GREENWICH TIME, in contrast with LOCAL MERIDIAN.
3220
meridian: grid
One of the GRID lines extending in a grid north-south direc­tion.