Sextant

Origin

From Latin sextāns, a bronze coin worth one-sixth of an as.

Full definition of sextant

Noun

1. (nautical) A navigational device for deriving angular distances between objects so as to determine latitude and longitude.
• 1918, Edgar Rice Burroughs, The Land That Time Forgot (novel) Chapter IVFor several days things went along in about the same course. I took our position every morning with my crude sextant; but the results were always most unsatisfactory. They always showed a considerable westing when I knew that we had been sailing due north. I blamed my crude instrument, and kept on.
2. (geometry) One sixth of a circle or disc; a sector with an angle of 60°.