Meaning of OCTANT in English

OCTANT

n. 1 an arc of a circle equal to one eighth of the circumference. 2 such an arc with two radii, forming an area equal to one eighth of the circle. 3 each of eight parts into which three planes intersecting (esp. at right angles) at a point divide the space or the solid body round it. 4 Astron. a point in a body's apparent course 45ø distant from a given point, esp. a point at which the moon is 45ø from conjunction or opposition with the sun. 5 an instrument in the form of a graduated eighth of a circle, used in astronomy and navigation.

[ L octans octant- half-quadrant f. octo eight ]

Concise Oxford English dictionary.      Краткий оксфордский словарь английского языка.