sextant
/ˈsekstənt/noun
- an instrument with a graduated arc of 60° and a sighting mechanism, used for measuring the angular distances between objects and especially for taking altitudes in navigation and surveying（航海或勘探用的）六分仪。
词源
late 16th cent. (denoting the sixth part of a circle)：from Latin sextans, sextant- 'sixth part', from sextus 'sixth'.