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| Latitude | The angular distance north or south of the earth's equator, measured in degrees along a meridian, as on a map or globe |
| Longitude | Lines that run from the North Pole to the South Pole and are equal in length on a map or globe |
| Degree | A unit of latitude or longitude, equal to 1/360 of the globe |
| Meridian | An imaginary circle on the earth's surface passing through the North and South Poles; a line or parallel of longitude |
| Parallel | Lines that do not intersect |
| Prime Meridian | The line of longitude that passes through Greenwich, England. designated as zero degrees longitude, and from which longitude east and west are measured |
| Relief | The shape of land formations on the earth's surface |
| Topographic map | A map that shows relief and the position of natural and man-made features |
| Terrain | A region or tract of land; the character (or topography) of a tract of land |
| Marginal Information | Instructions placed around the outer edge of a map |
| Bar scale | A ruler used to measure actual ground distances by converting distances on a map |
| legend | An explanatory description on a chart, map, or other illustration |
| Orient | To align or position oneself( or a map) in relationship to one's surroundings |
| Orienteering | A competitive form of land navigation in which each participant uses a map and compass to navigate between checkpoints |
| Declination | An angular difference between true north and either magnetic or grid north |
| True North | A line from any position on the earth's surface to the geographic North Pole; symbolized by a line with a star at the apex |
| Magnetic North | The direction to the north magnetic pole, as indicated by the north- seeking needle of a magnetic instrument |
| Grid North | The directioni of north that is established by using the vertical grid lines on a map |
| Statute mile | A unit of measurement that is approximately 5,280 feet |
| Nautical mile | A unit of measurement that is approximately 6,080 which is one minute of latitude; it is slightly longer than a statute mile |
| Grid zone | One of the 60 north-south divisions of the earth's surface between 84 degrees north latitude and 80 degrees south latitude, each 6 degrees wide |
| Bench mark | A surveyor's mark made on rocks or other permanent objects to indicate known elevations |
| Grid coordinate | A set of letters and numbers specifying the location of a point to the desired position within a 100,000 meter square |
| Superimpose | To place over or on top of something else |
| Universal Transverse Mercator Grid System | A grid system that has been designed to cover the part of the world between latitude 84 degrees north and latitude 80 degrees south, and, as its name implies, is imposed on the transverse Mercator projection |
| Grid lines | Lines that are regularly spaced at 1,000 or 10,000 meter intervals that make up the grid on a map |
| Grid square | the intersecting of north-south and east-west grid lines at 90- degrees angles to form a square |
| Mean sea level | The position of the level of the surface of the sea midway between high and low water |
| Hachure | A short, broken line used for showing relief on a map |
| Depression | A sunken or low place in the ground |
| Ridgeline | A line of high ground, usually with changes in elevation along its top |
| Concetric | Having a common center |
| Saddle | A low point between two areas of higher ground |
| Ridge | A sloping line of high ground |
| Sinkhole | A natural depression in a land surface communicating with a subterranean passage, generally occurring in limestone regions and formed by solution or by collapse of a cavern roof |
| Draw | A less developed stream course than a valley |
| Spur | A sloping line of high ground projecting out from the side of a ridge |
| Cut | A man-made feature resulting from the removal of high ground, usually to form a level area for roads or railroad |
| Fill | A man-made feature resulting from raising a low area, usually to form a level area for roads or railroad tracks |
| Concave | Curving inward, as the inside of a bowl |
| Convex | Curved outward, as the outside of a circle or sphere |
| Representative Fraction(RF) | The relationship of distance omeasured on a map to the corresponding distance on the ground; it is usually written as a fraction, such as if a map sheet is 1:50,000, RF is 1/50,000 |
| Center of mass | The point closest to the middle of an object |
| Azimuth | A horizontal angle usually measured clockwise in degrees from a north base line (direction) |
| Back azimuth | The opposite direction of an azimuth obtained by adding 180 degrees to or subtracting 180 degrees from an azimuth |
| Magnetic Azimuth | A direction that is expressed as the angular difference between magnetic north and a line of direction |
| Grid azimuth | The angle measured between grid north and a straight line plotted between two points on a map |
| Mil | A unit of angular measurement equal to 1/6400 of a complete revolution |
| Grid- Magnetic Angle (G-M Angle) | Angular difference in direction between grid north and magnetic north; it is measured east or west from grid north |
| Grid convergence | The horizontal angle at a point between true north and grid north |
| Field- expedient | Adapting to a particular |
