Io

1 of 2

noun

ˈī-(ˌ)ō

: a maiden loved by Zeus and changed by him into a heifer so that she might escape the jealous rage of Hera

I/O

2 of 2

abbreviation

input/output

Word History

Etymology

Noun

Latin, from Greek Iō

First Known Use

Noun

1563, in the meaning defined above

Time Traveler

The first known use of Io was in 1563

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Browse Nearby Words

in-your-face

I/O

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Cite this Entry

Style

“Io.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/Io. Accessed 4 Nov. 2025.

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Medical Definition

symbol

ionium

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Io

noun

abbreviation

Word History

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Medical Definition

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