octant

(ŏkˈtənt)

1. One eighth of a circle.
2. a. A 45° arc.
   b. The area enclosed by two radii at a 45° angle and the intersected arc.
3. An instrument based on the principle of the sextant but employing only a 45° angle, used as an aid in navigation.
4. Astronomy The position of a celestial body when it is separated from another by a 45° angle.
5. One of eight parts into which three-dimensional space is divided by three usually perpendicular coordinate planes.

Related Forms:

• oc·tanˈtal (ŏk-tănˈtəl) adjective