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• io
  io

  noun

  a small, solitary hawk, Buteo solitarius, having two plumage phases and breeding only on the Island of Hawaii, where it is a rare species and the only indigenous bird of prey: classified as near threatened.
• Io
  Io

  noun

  a woman who, being loved by Zeus, was transformed into a white heifer and was, at the wish of Hera, first guarded by Argus and later pursued through the world by a gadfly until she reached Egypt, where she resumed her true shape: identified by the Egyptians with Isis.
• Io.
  Io.

  abbreviation

  Iowa.
• I/O
  I/O

  inboard-outboard.
• I.O.
  I.O.

  abbreviation

  indirect object.

io

¹ American  

[ee-oh] / ˈi oʊ /

Or 'io

noun

ios plural

1. a small, solitary hawk, Buteo solitarius, having two plumage phases and breeding only on the Island of Hawaii, where it is a rare species and the only indigenous bird of prey: classified as near threatened.

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Io ² American  

[ahy-oh, ee-oh] / ˈaɪ oʊ, ˈi oʊ /

noun

1. Classical Mythology. a woman who, being loved by Zeus, was transformed into a white heifer and was, at the wish of Hera, first guarded by Argus and later pursued through the world by a gadfly until she reached Egypt, where she resumed her true shape: identified by the Egyptians with Isis.

2. Astronomy. a large volcanically active moon of the planet Jupiter.

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Io ³ American  

[ahy-oh, ee-oh] / ˈaɪ oʊ, ˈi oʊ /

noun

Ios plural

1. Io moth.

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Io ⁴ American  

Symbol, Chemistry.

1. ionium.

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Io. ⁵ American  

abbreviation

1. Iowa.

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I/O ⁶ American  

1. inboard-outboard.

2. Computers. input/output.

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I.O. ⁷ American  

Or IO,

abbreviation

1. indirect object.

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Io ¹ British  

/ ˈaɪəʊ /

noun

1. the innermost of the four Galilean satellites of Jupiter, displaying intense volcanic activity. Diameter: 3640 km; orbital radius: 422 000 km

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io ² British  

abbreviation

1. British Indian Ocean Territory

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Io ³ British  

/ ˈaɪəʊ /

noun

1. Greek myth a maiden loved by Zeus and turned into a white heifer by either Zeus or Hera

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I/O ⁴ British  

abbreviation

1. input/output

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Io ⁵ British  

symbol

1. ionium

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Io Scientific  

/ ī′ō,ē′ō /

1. One of the four brightest satellites of Jupiter and the fifth in distance from the planet. It was first sighted by Galileo.

2. See Note at moon

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Other Word Forms

Inflected Forms

noun

• Ios
  plural
• ios
  plural

Etymology

Origin of io

From Hawaiian ʿio

Example Sentences

“Juno had two really close flybys of Io during Juno’s extended mission,” Scott Bolton of the Southwest Research Institute in San Antonio, the mission’s principal investigator, said in a statement.

From Salon • Feb. 3, 2025

Slightly larger than Earth's moon, Io is the innermost of Jupiter's Galilean moons, which in addition to Io include Europa, Ganymede and Callisto.

From Science Daily • May 30, 2024

But although the planet is known to be smothered in volcanoes, an opaque atmosphere has prevented anyone from seeing an eruption the way spacecraft have spotted them on Io, the hypervolcanic moon of Jupiter.

From New York Times • May 27, 2024

The properties of TOI-6713.01 are perhaps most similar to those of the Jovian moon Io, where scientists recently discovered a lava lake as smooth as glass.

From Salon • May 14, 2024

It is even possible that the material outgassed from Io contributes, after many collisions and condensations, to the ring system of Jupiter.

From "Cosmos" by Carl Sagan