- (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.
- Synonym: compass (abbreviation)
- A supposed organ, in some animals, that allows then to align themselves with the Earth's magnetic field.
- 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)