octantal Definition

octant
noun

1a. math.
One eighth of the circumference of a circle;
1b. math.
A section, formed by drawing two straight lines from the centre to the circumference, of one eighth of a circle.
2. math.
A division of space or of a solid body divided into eight by three planes, usually at right angles to each other.
3. math.
An angle-measuring instrument in the form of a graduated eighth of a circle, used especially in astronomy and navigation.
4. astron, astrol.
A position of 45° from another position, especially of the Moon from conjunction (noun 4) or opposition (noun 7).

Derivative: octantal
adj

Etymology: 17c: from Latin octans half quadrant, from octo eight.