sky

American  

[skahy] / skaɪ /

noun

plural

skies

1. the region of the clouds or the upper air; the upper atmosphere of the earth.

   airplanes in the sky; cloudy skies.

2. the heavens or firmament, appearing as a great arch or vault.

3. the supernal or celestial heaven.

   They looked to the sky for help.

4. the climate.

   the sunny skies of Italy.

5. Obsolete. a cloud.

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verb (used with object)

skied, skyed, skying

1. Informal. to raise, throw, or hit aloft or into the air.

2. Informal. to hang (a painting) high on a wall, above the line of vision.

verb phrase

1. sky up (of prey, when flushed) to fly straight upward.

idioms

1. to the skies, with lavishness or enthusiasm; extravagantly: Also to the sky

   to praise someone to the skies.

2. out of a / the clear sky, without advance notice or warning; abruptly: Also out of athe clear blue sky

   An old beau phoned her out of a clear sky.

sky British  

/ skaɪ /

noun

1. (sometimes plural) the apparently dome-shaped expanse extending upwards from the horizon that is characteristically blue or grey during the day, red in the evening, and black at night

2. outer space, as seen from the earth

3. (often plural) weather, as described by the appearance of the upper air

   sunny skies

4. the source of divine power; heaven

5. informal the highest level of attainment

   the sky's the limit

6. highly; extravagantly

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verb

1. rowing to lift (the blade of an oar) too high before a stroke

2. informal (tr) to hit (a ball) high in the air

sky Scientific  

/ skī /

1. The atmosphere, as seen from a given point on the Earth's surface. The sky appears to be blue because the wavelengths associated with blue light are scattered more easily than those that are associated with the other colors.

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sky More Idioms  

More idioms and phrases containing sky

• blow sky-high
• out of a clear blue sky
• pie in the sky
• reach for the sky

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Other Word Forms

• skyless adjective
• skylike adjective

Etymology

Origin of sky

First recorded in 1175–1225; Middle English, from Old Norse skȳ “cloud,” cognate with Old English scēo “cloud”

Explanation

Want to see the sky? Go outside and look up! That’s assuming you’re not on Mars, of course. Everything you see above the surface of the Earth is the sky. Astronomers use the term "celestial sphere" for the sky. It's the space that includes everything we can see from our earthbound perspective, including clouds, stars, the sun, and the moon. If your uncle takes you out for ice cream and says, "The sky's the limit!" he means that there is no limit at all—you can order anything, even an enormous banana split.

Example Sentences

Scientists are also studying the formation of unusually large ice chunks called megacryometeors that can fall from the sky even on clear, sunny days.

From Los Angeles Times • Apr. 14, 2026

“We were more like free souls, ‘the sky is the limit,’” he says.

From The Wall Street Journal • Apr. 13, 2026

McIlroy hugged his caddie Harry Diamond, looked to the sky and let out a roar as he raised him arms aloft - his sixth major title cementing his place as one of the sport's greats.

From BBC • Apr. 12, 2026

In the event, according to Nasa's TV coverage, the angle of attack was perfect and the capsule hit a narrow target of sky southeast of Hawaii as it headed for the Californian coast.

From BBC • Apr. 11, 2026

At last he dragged his gaze from the sky, and sat down by the fire.

From "Wolf Brother" by Michelle Paver