[ ahy-suh-pawr ]
/ ˈaɪ səˌpɔr /
an imaginary line on the earth's surface connecting points of equal annual change in the declination, inclination, or other components of the earth's magnetic field.
Also called isoporic line.
Related formsi·so·por·ic, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019