Aclinic line

From Glossary of Meteorology

aclinic line

(Or dip equator, magnetic equator.) The line through those points on the earth's surface at which the magnetic inclination is zero.

The aclinic line is a particular case of an isoclinic line. In South America the aclinic line lies at about 15°S latitude, while from central Africa to about Indochina it coincides approximately with the parallel of 10°N latitude.
Compare agonic line, geomagnetic equator.