W2S2 [skaı] n plural skies
[Date: 1200-1300; : Old Norse; Origin: 'cloud']
1.) [singular, U]
the space above the earth where clouds and the sun and stars appear
The sky grew dark, and a cold rain began to fall.
A shooting star sped across the sky.
in the sky
There wasn't a cloud in the sky.
blue/black/grey etc sky
The sun rose higher in a clear blue sky.
clear/cloudy/dark etc sky
Robyn lay on her back looking up at the cloudless sky.
under a slightly overcast sky (=with clouds)
night/morning/summer etc sky
The evening sky was darkening as I made my way home.
She looked out over the rooftops and the open sky .
2.) skies [plural]
a word meaning 'sky', used especially when describing the weather or what the sky looks like in a place
a land of blue skies and warm sunshine
The skies were overcast, and it was chilly and damp.
3.) the sky's the limit
spoken used to say that there is no limit to what someone can achieve, spend, win etc
Francis believes the sky's the limit for the young goalkeeper.
pie in the sky atpie, praise sb/sth to the skies atpraise1 (1)

Dictionary of contemporary English. 2013.