Definitions for loadstoneˈloʊdˌstoʊn
Random House Webster's College Dictionary
a permanent magnet consisting of magnetite that possess polarity and has the power to attract as well as to be attracted magnetically
alt. of Lodestone
The Nuttall Encyclopedia
or Lodestone, an iron ore remarkable for its magnetic quality or power of attracting iron; it derived its name from its use as a leading stone in the compass to mariners.