1.
a. A device used to determine geographic direction, usually consisting of a magnetic needle or needles horizontally mounted or suspended and free to pivot until aligned with the magnetic field of Earth. b. Another device, such as a radio compass or a gyrocompass, used for determining geographic direction.
2. A V-shaped device for describing circles or circular arcs and for taking measurements, consisting of a pair of rigid, end-hinged legs, one of which is equipped with a pen, pencil, or other marker and the other with a sharp point providing a pivot about which the drawing leg is turned. Also called pair of compasses.
3. a. An enclosing line or boundary; a circumference: outside the compass of the fence. See synonyms at circumference. b. A restricted space or area: four huge crates within the compass of the elevator. c. Range or scope, as of understanding, perception, or authority: "Lacking a coherent intellectual and moral commitment, [he] was forced to find his compass in personal experience" (Doris Kearns Goodwin). See synonyms at range.
[Middle English compas, circle, compass, from Old French, from compasser, to measure, from Vulgar Latin *compassāre, to pace off : Latin com-, com- + Latin passus, step. See