名詞 octant:

1. a measuring instrument for measuring angles to a celestial body; similar to a sextant but with 45 degree calibration

oc.tant

n.（名詞）
One eighth of a circle.
八分圓：圓的八分之一

A 45= arc.
45°弧
The area enclosed by two radii at a 45= angle and the intersected arc.
八分圓：一個(gè)被兩條成45°角的半徑及與之相交的弧所包圍的區(qū)域
An instrument based on the principle of the sextant but employing only a 45= angle, used as an aid in navigation.
八分儀：以六分儀的規(guī)則為基礎(chǔ)設(shè)計(jì)的一種儀器，但只采用45°角，用來幫助航海
Astronomy The position of a celestial body when it is separated from another by a 45= angle.
【天文學(xué)】 八分圓：一個(gè)天體當(dāng)它成45°角與另一天體分離時(shí)所處的位置
One of eight parts into which three-dimensional space is divided by three usually perpendicular coordinate planes.
卦限：八個(gè)區(qū)之一，這八個(gè)區(qū)是由三個(gè)正交平分割三維空間而成

來源：
Latin oct3ns octant-
拉丁語 oct3ns octant-
from octô [eight] * see oktô(u)
源自 octô [八] *參見 oktô(u)

【引伸】
octan.tal