Octant

Part of speech: noun

Definitions

1. In geometry, this term refers to any of the eight divisions created in three-dimensional Cartesian coordinates by the intersection of coordinate planes
2. It is commonly understood as a specific sector of space formed by dividing the whole volume into eight sections based on positive and negative values of the coordinates
3. This term denotes one of the eight sections in three-dimensional space that result from the intersection of coordinate planes for spatial analysis

Etymology: An octant is one of the eight divisions of a circle or sphere, and the instrument built on that principle was named for the arc it measured. The English word comes from Latin "octans," meaning an eighth part, built on "octo," eight. The same Latin root gives us "octave," "October," and "octopus," all of which share the idea of eight. The word also has a doublet, Octans, which is the name of a faint southern constellation, so the two forms are the same Latin word reaching English along different paths. The sense of a navigational instrument came from the arc of one-eighth of a circle that the device measured, which is how a term for a fraction of space ended up naming a tool for finding one's position at sea.