octant

[ ok-tuhnt ]

noun

1. the eighth part of a circle.
2. Mathematics. 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.
5. Octant, Astronomy. the constellation Octans.

octant

/ ˈɒktənt /

noun

1. maths
   1. any of the eight parts into which the three planes containing the Cartesian coordinate axes divide space
   2. an eighth part of a circle
2. astronomy the position of a celestial body when it is at an angular distance of 45° from another body
3. an instrument used for measuring angles, similar to a sextant but having a graduated arc of 45°

Other Words From

• oc·tan·tal [ok-, tan, -tl], adjective

Word History and Origins

Origin of octant¹

First recorded in 1680–90; from Latin octant- (stem of octāns ); Octans

Word History and Origins

Origin of octant¹

C17: from Latin octans half quadrant, from octo eight

Example Sentences

Thus fig. 59 conveniently represents an octant of the wave surface, which cuts each coordinate plane in a circle and an ellipse.

From Project Gutenberg

It is the sextant or some member of the sextant family - such as the quadrant, octant, etc.

From Project Gutenberg

A third staff (or an octant) was fixed at the end of the horizon-staff, and upon it the angle observed could be read off.

From Project Gutenberg

The third plane will lie horizontal or equatorial, and will divide each of these quarters into an upper and lower octant.

From Project Gutenberg

Excluded, of course, are those instruments normally made of wood, such as the octant and the mariners quadrant.

From Project Gutenberg