The Collaborative International Dictionary
magnetic compass \magnetic compass\ n. An device using a magnet (such as a magnetic needle) to indicate the direction of magnetic north.
Wiktionary
n. (context military nautical English) An instrument containing a freely suspended magnetic element which displays the direction of the horizontal component of the Earth’s magnetic field at the point of observation.
WordNet
n. compass based on an indicator (as a magnetic needle) that points to the magnetic north
Usage examples of "magnetic compass".
You can't carry a damn great gyro weighing about half a ton on your back, and a magnetic compass is useless in those latitudes.
The gadget would point him away from New York for half his trip, and an ordinary magnetic compass would serve to show which way.
It's a magnetic compass, of course, and that's useless because I do know the magnetic north pole is nowhere near the geographical north pole: I believe it's about a thousand miles away from it.
A magnetic compass may be no use here, but I can keep myself oriented by the heavens.
Apart from Jackstraw and myself, there probably wasn't a handful of people in all Greenland who could start that damned Citroen, far less drive it, only Jackstraw could handle the dogs, and it was long odds indeed against any of the passengers knowing anything at all about astral or magnetic compass navigation - the latter very tricky indeed in these high latitudes.
I suppose that after Smallwood had gone far enough to consider that we would never be able to reach that point, he had cut loose dogs and dog-sledge as a needless encumbrance - but not before he had severed all the traces attaching the dogs to the sledge and, I noticed grimly, removed all the wraps and the magnetic compass that had been there.
Have to be careful using a magnetic compass this far north, you know.
A century later, the Spanish king Alfonso the Wise -who had also commissioned a great chart of the stars - decreed that all his ships should carry the ‘magnetic compass’.
A more likely explanation was the inaccuracy of either man's magnetic compass.