1. an eighth of a circle; 45° angle or arc
2. an instrument like the sextant, for measuring angles
3. Astronomy the position of one celestial body when it is 45° distant from another
4. Ancient Mathematics any of the eight parts into which a space is divided by three planes intersecting at a single point and at right angles to one another
Webster’s New World College Dictionary, Fourth Edition, compiled by the
editors of Webster’s New World Dictionaries. Copyright © 2010 by Houghton
Mifflin Harcourt. Published by Houghton Mifflin Harcourt. All rights reserved.