Octant /(?)/

Oc·tant

Octant

n.
  1. The eighth part of a circle; an arc of 45 degrees. (Geom.)
  2. The position or aspect of a heavenly body, as the moon or a planet, when half way between conjunction, or opposition, and quadrature, or distant from another body 45 degrees. (Astron. & Astrol.)
  3. An instrument for measuring angles (generally called a quadrant), having an arc which measures up to 9O°, but being itself the eighth part of a circle. Cf. Sextant.
  4. One of the eight parts into which a space is divided by three coordinate planes. (Math. & Crystallog.)