1. (Science: mathematics) The sixth part of a circle.
2. An instrument for measuring angular distances between objects, used especially. at sea, for ascertaining the latitude and longitude. It is constructed on the same optical principle as Hadley's quadrant, but usually of metal, with a nicer graduation, telescopic sight, and its arc the sixth, and sometimes the third, part of a circle. See Quadrant.
Origin: L. Sextans, -antis, the sixth part of an as, fr. Sextus sixth, sex six. See Six.