I. | ̷ ̷(ˌ) ̷ ̷ at iso- + adjective
Etymology: International Scientific Vocabulary is- + magnetic
: of, relating to, or marked by points of equal magnetic intensity or points of equal value of a component of such intensity
an isomagnetic chart
II. noun
: a line on a map or chart of the earth's surface connecting points of equal magnetic intensity or points of equal value of a component of such intensity