Sex"tant (?), n. [L. sextans, -antis, the sixth part of an as, fr.
sextus sixth, sex six. See Six.] 1. (Math.) The sixth part of a circle.
2. 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.