aclinic line

from WordNet (r) 3.0 (2006)

aclinic line
    n 1: an imaginary line paralleling the equator where a magnetic
         needle has no dip [syn: {aclinic line}, {magnetic equator}]

from The Collaborative International Dictionary of English v.0.48

magnetic equator \magnetic equator\ n.
   An imaginary line paralleling the equator where a magnetic
   needle has no dip, the dipping needle being horizontal;
   called also {aclinic line}.
   [WordNet 1.5]