octant

oc·tant  (ktnt)

n.

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.

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[Latin octns, octant-, from oct, eight; see okt(u) in Indo-European roots.]

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oc·tantal (k-tntl) adj.

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octant [ˈɒktənt]

n

1. (Mathematics) Maths

a.  any of the eight parts into which the three planes containing the Cartesian coordinate axes divide space

b.  an eighth part of a circle

2. (Astronomy) Astronomy the position of a celestial body when it is at an angular distance of 45° from another body

3. (Mathematics & Measurements / Navigation) an instrument used for measuring angles, similar to a sextant but having a graduated arc of 45°

[from Latin octans half quadrant, from octo eight]

Thesaurus

Noun

1.

octant - a measuring instrument for measuring angles to a celestial body; similar to a sextant but with 45 degree calibration limb - the graduated arc that is attached to an instrument for measuring angles; "the limb of the sextant" measuring device, measuring instrument, measuring system - instrument that shows the extent or amount or quantity or degree of something