WordReference Random House Unabridged Dictionary of American English © 2026
i•so•por
(ī′sə pôr′),USA pronunciation n.
i′so•por′ic, adj.
- 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 i′sopor′ic line′.
- Greek póros path, pore2
- iso- + -por 1930–35