\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}.
3. (Astron.) The constellation Sextans.
{Box sextant}, a small sextant inclosed in a cylindrical case
   to make it more portable.