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Glite Dictionary
isogonic line

isogonic line

9.9
A line on a map connecting places with the same difference between magnetic north and true north
  • noun
  • /ˌaɪsəˈɡɒnɪk laɪn/
  • Specialized
translation icon : línea isogónica
  • An isogonic line connects points on a map where the magnetic declination is equal.

Examples

  • As you move across an isogonic line, the magnetic declination remains unchanged.

  • The navigator charted the ship's course using an isogonic line to correct for magnetic variation.

  • Maps often display isogonic lines to help pilots determine true directions.

  • The isogonic line indicates areas of equal magnetic declination.

  • Many maps include isogonic lines for navigation.

  • Maps often display isogonic lines to help pilots determine true directions.

  • The navigator charted the ship's course using an isogonic line to correct for magnetic variation.

Synonyms

isogone
vsisogonic line
  • Specialized
9.9

A line on a map showing places where compasses point the same amount away from north

is drawn on maps and specifies equality at a given time
isogonal line
vsisogonic line
  • Specialized
9.9

A line on the Earth's surface joining places where compasses point the same amount from true north

is drawn on maps and specifies equality at a given time

Surface Forms

isogonic line singular
isogonic lines plural

Morphology

isogonic + line

Although 'line' is transparent, 'isogonic' is a rare, technical formation whose connection to 'magnetic declination' is not derivable from its parts for an average B1 learner. The term requires domain-specific knowledge (geomagnetism/cartography) rather than ordinary compositional meaning, so the overall MWE is not predictable from its constituents.

Etymology

The term isogonic line comes from parts meaning iso for 'equal' and gonic for 'angle', and it describes an imaginary line on a map that joins places where a compass points the same amount away from 'true north'. So, following an isogonic line keeps the 'compass error' the same, which helps pilots and sailors correct their direction.