**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.