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Definition of "octant" [oc•tant]

  • One eighth of a circle. (noun)
  • A 45° arc. (noun)
  • The area enclosed by two radii at a 45° angle and the intersected arc. (noun)
  • An instrument based on the principle of the sextant but employing only a 45° angle, used as an aid in navigation. (noun)
  • Astronomy The position of a celestial body when it is separated from another by a 45° angle. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Use "octant" in a sentence
  • "John Paul’s deliverance from the hardship of the lower deck was a brass instrument called an octant."
  • "Advances in the development of these instruments made such calculations easier and more precise, for example: the "course protractor", the "cuadrant", the "octant and the sextant", and the "longitude clock", which was a precision chronometer."
  • "From a private collection, offerings include several important pairs of globes by Newton, a sextant by Ramsden, an octant by George Jones, equinoctial dials, astrolabes, chronometers, microscopes and nautical antiques."