Webster's Revised Unabridged Dictionary · 1913

Sky

Sky (skī) , noun

[Old English skie a cloud, Icelandic skȳ; akin to Swedish & Danish sky; compare Anglo-Saxon scūa, scūwa, shadow, Icelandic skuggi; probably from the same root as English scum. r158. See Scum, and compare Hide skin, Obscure.]

1.
A cloud. [Obsolete]
[A wind] that blew so hideously and high, That it ne lefte not a sky In all the welkin long and broad. — Chaucer
2.
Hence, a shadow. [Obsolete]
She passeth as it were a sky. — Gower
3.
The apparent arch, or vault, of heaven, which in a clear day is of a blue color; the heavens; the firmament; -- sometimes in the plural.
The Norweyan banners flout the sky. — Shakespeare
4.
The weather; the climate.
Thou wert better in thy grave than to answer with thy uncovered body this extremity of the skies. — Shakespeare

Sky is often used adjectively or in the formation of self-explaining compounds; as, sky color, skylight, sky-aspiring, sky-born, sky-pointing, sky-roofed, etc.

Collocations (3)
Sky blue , an azure color.
Sky scraper (Nautical) , a skysail of a triangular form. — Totten
Under open sky , out of doors. Under open sky adored. — Milton

Sky , transitive verb

1.
To hang (a picture on exhibition) near the top of a wall, where it can not be well seen. [Colloquial]
Brother Academicians who skied his pictures. — The Century
2.
To throw towards the sky; as, to sky a ball at cricket. [Colloquial]