A sextant is a navigation instrument used to measure the angle between two visible objects, most famously between the horizon and a celestial body like the Sun, Moon, or a star, in order to find a ship’s position (latitude and longitude) at sea.

Quick meaning

  • In plain terms, a sextant is a very precise angle-measuring tool.
  • Sailors use it to “shoot” the Sun or stars above the horizon, then use tables or calculations to figure out where they are on Earth.
  • The name comes from Latin sextans or sextus , meaning “one‑sixth,” because its arc spans 60 degrees, which is one‑sixth of a full circle.

How it works (simple picture in your head)

Imagine you’re on a ship:

  1. You look through a small telescope on the sextant at the horizon.
  2. A movable arm and mirrors let you “bring down” the image of the Sun or a star until it appears to sit exactly on the horizon line.
  3. The angle shown on the sextant’s scale is the height (altitude) of that celestial body above the horizon.

With that angle plus the exact time (from a clock) and special tables, you can work out your position on the globe—this is classic celestial navigation.

Extra nuance

  • It isn’t a modern slang word; it’s an old but still respected seafaring tool.
  • Today, GPS does almost all the work, but many sailors still learn sextant use as a backup and a tradition.

TL;DR: “Sextant” means a classic seafaring instrument that precisely measures angles (usually between the horizon and a celestial body) to figure out where you are on Earth.

Information gathered from public forums or data available on the internet and portrayed here.