sextant

plural sextants

1. nauticalA navigational device for deriving angular distances between objects so as to determine latitude and longitude.

   I took our position every morning with my crude sextant; but the results were always most unsatisfactory.

   1918 September–November, Edgar Rice Burroughs, “The Land That Time Forgot”, in The Blue Book Magazine, Chicago, Ill.: Story-press Corp., →OCLC; republished as chapter IV, in Hugo Gernsback, editor, Amazing Stories, (please specify |part=I to III), New York, N.Y.: Experimenter Publishing, 1927, →OCLC

   2 more examples

   […] I can do more with a Quadrant, Sextant or Octant, of 1 foot Radius, furniſhed with Teleſcopical Sights and Screws, then ^([sic]) can poſſibly be done with any other Inſtrument, furniſhed only with Common Sights, though 10, 20, 30, nay threeſcore foot Radius; […]

   1674, Robert Hooke, Animadversions on the Firſt Part of the Machina Coelestis of the […] Aſtronomer Johannes Hevelius […] , page 43

   Moskowitz and Devereux have designed a hyperaccurate sextant for interstellar navigation based upon the design of the sextant used by the Apollo astronauts.

   1981, Saul Adelman, Benjamin Adelman, Bound for the Stars, →ISBN, page 227

2. geometryOne sixth of a circle or disc; a sector with an angle of 60°.
3. dentistryOne of six groups of adjacent teeth, excluding the wisdom teeth.
4. biologyA radial cell division of segments in three series, a sixth part of the original.

1. astronomyThe constellation Sextans.