(1):
(n.) The constellation Sextans.
(2):
(n.) An instrument for measuring angular distances between objects, - used esp. 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.
(3):
(n.) The sixth part of a circle.