- (military, nautical) 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.
- A supposed organ, in some animals, that allows then to align themselves with the Earth's magnetic field.
- compass (abbreviation)
- “magnetic compass” in the Collins English Dictionary, Glasgow: HarperCollins Publishers.
- “magnetic compass” (US) / “magnetic compass” (UK) in Oxford Dictionaries, Oxford University Press.
- “magnetic compass” in Merriam-Webster Online Dictionary, Merriam-Webster Online.
- JP 1-02 Department of Defense Dictionary of Military and Associated Terms
- Page 673, Webster's II New College Dictionary
- Page 215, The Military Dictionary, DIANE Publishing, 1987
- Page 425, A dictionary of Science, Literature and Art, William Thomas Brande, 1866 (plural form is defined)