Oc"tant (?), n. [L. octans, -antis. fr. octo eight. See Octave.]
1. Geom.
The eighth part of a circle; an arc of 45 degrees.
2. Astron. & Astrol.
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.
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. Math. & Crystallog.
One of the eight parts into which a space is divided by three coordinate planes.
© Webster 1913.