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1. One eighth of a circle.
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.

[Latin octāns, octant-, from octō, eight; see oktō(u) in Indo-European roots.]

oc·tan′tal (ŏk-tăn′təl) adj.


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. (Navigation) an instrument used for measuring angles, similar to a sextant but having a graduated arc of 45°
[C17: from Latin octans half quadrant, from octo eight]


(ˈɒk tənt)

1. the eighth part of a circle.
2. any of the eight parts into which three mutually perpendicular planes divide space.
3. an instrument having an arc of 24°, used by navigators for measuring angles up to 90°.
4. the position of one heavenly body when 45° distant from another.
[1680–90; < Latin octant-, s. of octāns=oct(ō) eight + -āns, as in quadrāns quadrant]
oc•tan′tal (-ˈtæn tl) adj.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.octant - a measuring instrument for measuring angles to a celestial bodyoctant - 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
References in classic literature ?
It was in its octant, and showed a crescent finely traced on the dark background of the sky.
Managers not only developed the new processes they needed to support the new technology but also with the help of Octant positioned Utica to compete for business outside of Ford.
Contractor address : 3 rue d~ Octant Zone Sud Galaxie Parc technologique des petites pres
By breaking the surface into eight octant petals in two florets, he develops a unique projection that had by far the most isometric mapping geometry to that date (although at the cost of a set of crosscuts that split some of the continents).
1-6): "Alatina with tall, narrow bell, flared at base, tapering into truncated pyramid at apex; 4 crescentric gastric phacellae at interradial corners of stomach; 3 simple to palmate branching velarial canals per octant, each with a velarial lappet bearing a row of 3 to 4 nematocyst warts; 4 long, wing-like (sensu Reynaud, 1830) pedalia, each with a pink tentacle.
Of necessity it was latitude that was relied on for navigation, being readily observed after the invention of Hadley's octant in 1731 and Campbell's sextant in 1757, both of which however, again because of cost, took decades to become common in merchant vessels.
3) Finding a polynomial representation of V and W by performing an adequate change of coordinates in each octant of [R.
Assume that O be the origin of the x, y, z axes, T be the trisector line x = y = z of the positive octant.
QI HAVE a four-ring York stone octant in my back garden but the slabs are covered in algae.
I have a four-ring Yorkstone octant surrounded with Astroturf in my garden.
If O is the origin of the x,y, z axes, (t) the trisector line x = y = z of the positive octant and n the plane x + y + z = 0 passing through the origin (O) and perpendicular to (t), then the tricomplex number u can be described by the projection S of the segment OP along the line (t), by the distance D from P to the line (t), and by the azimuthal angle 0 in the n plane.