Isogonic lines Meaning, Definition & Usage

  1. noun an imaginary line connecting points on the Earth's surface where the magnetic declination is the same
    isogonal line; isogone; isogonic line.

WordNet


Definitions
  1. (Magnetism), lines traced on the surface of the globe, or upon a chart, connecting places at which the deviation of the magnetic needle from the meridian or true north is the same.

Webster 1913