an imaginary line on the earth's surface along which true north and magnetic north are identical, and a compass needle makes no angle with the meridian
An imaginary line on the earth's surface connecting points where the magnetic declination is zero.
Origin of agonic lineGreek agōnos, having no angle (a-, without; see a–1 + gōniā, angle; see diagonal) + –ic.
(plural agonic lines)
- (cartography, navigation) A line on a chart or map joining points of zero magnetic declination.