MAGNETICVARIATION
magnetic variation
Noun
- In navigation, at a given place and time, the horizontal angle between the true north and magnetic north measured east or west according to whether magnetic north lies east or west of true north.
- In cartography, the annual change in direction of the horizontal component of the Earth’s magnetic field.
The above text is a snippet from Wiktionary: magnetic variation
and as such is available under the Creative Commons Attribution/Share-Alike License.