[sek-stuh
nt] 
| 1. | an astronomical instrument used to determine latitude and longitude at sea by measuring angular distances, esp. the altitudes of sun, moon, and stars. |
| 2. | (initial capital letter) Astronomy. the constellation Sextans. |
| Sex·tans (sěks'tənz) n. A constellation in the equatorial region of the sky near Leo and Hydra. Also called Sextant. [New Latin sextāns, sextant; see sextant.] |
| sex·tant (sěk'stənt) n.
[New Latin sextāns, sextant-, from Latin, sixth part (so called because the instrument's arc is a sixth of a circle), from sextus, sixth; see s(w)eks in Indo-European roots.] |
| sextant (sěk'stənt) Pronunciation Key
An instrument containing a graduated 60° arc and a movable pivoted arm corresponding to the radius of the arc's circle, used in celestial navigation to measure the altitude of a celestial body in order to determine the observer's latitude and longitude. A horizontally mounted telescope and two small mirrors are arranged so that the observer can, by moving the pivoted arm, sight the horizon and the reflected image of the celestial body in the same line, giving a reading along the arc that is used to look up the observer's position in a published table. |