Definition of "octant" in English

noun

1. The eighth part of a circle; an arc of 45 degrees.

2. (astrology) The aspect of two planets that are 45°, or one-eighth of a circle, apart.

3. (geometry) The eighth part of a disc; a sector of 45 degrees; half a quadrant.

4. (nautical) An instrument for measuring angles, particularly of elevation.