1. (n.) The sixth part of a circle.

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 constellation Sextans.

astrolabe astronavigation azimuth circle azimuth compass bevel bevel protractor bevel square celestial navigation chronometer clinometer coastwise navigation consolan crescent dead reckoning fix goniometer graphometer half circle hemicycle line of position loran pantometer pilotage plane sailing point-to-point navigation protractor quadrant radar radio beacon radio navigation radiogoniometer sector semicircle shoran sofar sonar tables theodolite transit transit circle transit instrument transit theodolite