octant

One eighth of a circle.

A 45° arc.

The area enclosed by two radii at a 45° angle and the intersected arc.

An instrument based on the principle of the sextant but employing only a 45° angle, used as an aid in navigation.

The position of a celestial body when it is separated from another by a 45° angle.

One of eight parts into which three-dimensional space is divided by three usually perpendicular coordinate planes.

Each of the eight regions into which space is divided by three copunctal non-costraight planes.

The eighth part of a circle.

In astronomy, that position or aspect of two heavenly bodies, especially a planet and the sun, when half-way between conjunction or opposition and quadrature, or distant from one another by the eighth part of a circle, or 45°.