Definitions for IOˈaɪ oʊ, ˈi oʊ

This page provides all possible meanings and translations of the word IO

Princeton's WordNet

  1. Io(noun)


  2. Io(noun)

    the closest of Jupiter's moons; has active volcanoes


  1. Io(prop. n.)

    One of the large moons of the planet Jupiter, remarkable for its intense volcanic activity, as observed in fly-bys of space probes. It was named after the mythological Io. The remarkable images of Io and Jupiter obtained by the Galileo 2 space probe to Jupiter and Hubble photographs are available at the web site of NASA. Reproduced here are:

  2. Origin: [Gr. 'Iw`.]


  1. io(Noun)

    A type of moth, the io moth.

  2. Io(ProperNoun)

    The daughter of Inachus.

  3. Io(ProperNoun)

    A moon of Jupiter, known for its volcanic activity, peppered with about 400 active volcanoes.

  4. Origin: Modern , from .

Webster Dictionary

  1. Io(noun)

    an exclamation of joy or triumph; -- often interjectional

  2. Origin: [L.; cf. Gr. "iw`.]


  1. Io

    Io is the innermost of the four Galilean moons of the planet Jupiter and, with a diameter of 3,642 kilometres, the fourth-largest moon in the Solar System. It was named after the mythological character of Io, a priestess of Hera who became one of the lovers of Zeus. With over 400 active volcanoes, Io is the most geologically active object in the Solar System. This extreme geologic activity is the result of tidal heating from friction generated within Io's interior as it is pulled between Jupiter and the other Galilean satellites—Europa, Ganymede and Callisto. Several volcanoes produce plumes of sulfur and sulfur dioxide that climb as high as 500 km above the surface. Io's surface is also dotted with more than 100 mountains that have been uplifted by extensive compression at the base of the moon's silicate crust. Some of these peaks are taller than Earth's Mount Everest. Unlike most satellites in the outer Solar System, which are mostly composed of water ice, Io is primarily composed of silicate rock surrounding a molten iron or iron sulfide core. Most of Io's surface is characterized by extensive plains coated with sulfur and sulfur dioxide frost. Io's volcanism is responsible for many of the satellite's unique features. Its volcanic plumes and lava flows produce large surface changes and paint the surface in various shades of yellow, red, white, black, and green, largely due to allotropes and compounds of sulfur. Numerous extensive lava flows, several more than 500 km in length, also mark the surface. The materials produced by this volcanism provide material for Io's thin, patchy atmosphere and Jupiter's extensive magnetosphere. Io's volcanic ejecta also produce a large plasma torus around Jupiter.

Chambers 20th Century Dictionary

  1. Io

    ī′ō, n. an exclamation of joy or triumph. [L.]

The Nuttall Encyclopedia

  1. Io

    in the Greek mythology a daughter of Inachos (q. v.), beloved by Zeus, whom Hera out of jealousy changed into a heifer and set the hundred-eyed Argus to watch, but when Zeus had by Hermes slain the watcher, Hera sent a gadfly to goad over the world, over which she ranged distractedly till she reached Egypt, where Osiris married her, and was in connection with him worshipped as Isis.


  1. Chaldean Numerology

    The numerical value of IO in Chaldean Numerology is: 8

  2. Pythagorean Numerology

    The numerical value of IO in Pythagorean Numerology is: 6

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