noun
sextant
SEK-stənt
Sextant (noun) means a navigational instrument with a graduated arc and mirrors, used to measure the angle between a celestial body and the horizon in order to work out latitude and position at sea. Example: “He took a noon sight with the sextant to fix their latitude.”
noun
1
A navigational instrument with a graduated arc and mirrors, used to measure the angle between a celestial body and the horizon in order to work out latitude and position at sea.
"He took a noon sight with the sextant to fix their latitude."
"Before satellite navigation, every deck officer could use a sextant."
2
geometry, rare A sixth part of a circle, an arc of sixty degrees.
"The arc marked out a sextant of the full circumference."
How to use sextant
Learner’s notesIn plain EnglishA mirrored instrument sailors use to find their position from the sun or stars.
When to use it
Neutral; nautical and historical contexts.
Easily confused with
Common pairings
take a sight with a sextant
a marine sextant
sextant altitude
shoot the sun
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He took a noon sight with the _____ to fix their latitude.
Etymology
From Latin sextans 'a sixth part', because the instrument's graduated arc spans a sixth of a circle, that is sixty degrees.
Synonyms
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Frequently asked questions
How does a sextant work?
You look at the horizon through a half-silvered mirror and swing an arm carrying a second mirror until the reflected image of the sun or a star sits exactly on that horizon line. The angle read off the arc, combined with the exact time and published tables, gives your position.
What is the difference between a sextant and an astrolabe?
An astrolabe is an older instrument, held hanging vertically, that measures a body's altitude against a fixed scale and is hard to use on a moving deck. A sextant uses mirrors to bring the body and the horizon into the same view, so it stays accurate on a pitching ship and is far more precise.
Are sextants still used?
Yes, though rarely as the primary method. Merchant and naval officers still train in celestial navigation as a backup for GPS failure or jamming, and ocean sailors carry a sextant for the same reason.
What is the meaning of sextant?
"sextant" (noun) means a navigational instrument with a graduated arc and mirrors, used to measure the angle between a celestial body and the horizon in order to work out latitude and position at sea.
