also sky-light, 1670s, "light from the sky," from sky (n.) + light (n.). The meaning "small window or opening in a roof or ceiling to admit light" is recorded from 1680s. Sky-lit (adj.) is attested by 1923.

1680s, type of firework that flies high, from sky (n.) + rocket (n.2). The verb, in the figurative sense of "to rise abruptly and rapidly" (often with suggestion of "and then explode and vanish") is attested from 1895. As rhyming slang for "pocket," by 1879.

"to hit a ball high in the air," 1856, originally in golf, from loft (n.). Compare sky (v.) in the modern slang sense. An earlier sense was "to put a loft on" (a building), 1560s; also "to store (goods) in a loft" (1510s). Related: Lofted; lofting.

also sky-scraper, "very tall urban building," 1888, in a Chicago context, from sky (n.) + agent noun of scrape (v.). Used earlier for any thing which reaches or extends far up, such as "ornament atop a building" (1883), "very tall man" (1857), "high-flying bird" (1840), "light sail at the top of a mast" (1794), and the name of a racehorse (1789). Compare cognate French gratte-ciel, from gratter "to scrape" + ciel "sky;" German Wolkenkratzer, from Wolke "cloud" + Kratzer "scraper."

cloud-cleaver, an imaginary sail jokingly assumed to be carried by Yankee ships. [W. Clark Russell, "Sailors' Word Book," 1883]

"to hijack an airplane," by August 1961 in U.S. newspapers, apparently coined in headlines in New York Mirror and others, from sky (n.) + second element abstracted from hijack (q.v.).

From hijack to skyjack is no more than a twitch of a headline writer's pencil, and thus America is introduced to a new colloquialism that is thoroughly understood. For general use, however, the word hijack colorfully persists, and skyjack is likely to enjoy ephemeral usage. [editorial, Stockton (Calif.) Record, Aug. 21, 1961]

Related: Skyjacked; skyjacking; skyjacker (1961).

Proto-Indo-European root meaning "to cover, conceal."

It forms all or part of: chiaroscuro; cunnilingus; custody; cutaneous; cuticle; -cyte; cyto-; hide (v.1) "to conceal;" hide (n.1) "skin of a large animal;" hoard; hose; huddle; hut; kishke; lederhosen; meerschaum; obscure; scum; skewbald; skim; sky.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit kostha "enclosing wall," skunati "covers;" Greek kytos "a hollow, vessel," keutho "to cover, to hide," skynia "eyebrows;" Latin cutis "skin," ob-scurus "dark;" Lithuanian kiautas "husk," kūtis "stall;" Armenian ciw "roof;" Russian kishka "gut," literally "sheath;" Old English hyd "a hide, a skin," hydan "to hide, conceal; Old Norse sky "cloud;" Old English sceo "cloud;" Middle High German hode "scrotum;" Old High German scura, German Scheuer "barn;" Welsh cuddio "to hide."

also sky-lark, "to frolic or play, engage in boisterous fun," 1809, originally nautical, in reference to "wanton play about the rigging, and tops," probably from skylark (n.), and influenced by lark (n.2). The source and the influence might be the reverse. Related: Skylarked; skylarking.

"sky-colored, sky-blue," 1660s, with -an + Latin caeruleus "blue, dark blue, blue-green," perhaps from a dissimilation of caelulum, diminutive of caelum "heaven, sky," which is of uncertain origin (see celestial). The Latin word was applied by Roman authors to the sky, the Mediterranean, and occasionally to leaves or fields. The older adjective in English was ceruleous (1570s). As a noun, from 1756. The artist's cerulean blue is from 1885.

late 14c., "pertaining to the sky or the visible heavens; pertaining to the Christian or pagan heaven," from Old French celestial "celestial, heavenly, sky-blue," from Latin caelestis "heavenly, pertaining to the sky," from caelum "heaven, sky; abode of the gods; climate," which is of uncertain origin; perhaps from PIE *kaid-slo-, perhaps from a root also found in Germanic and Baltic meaning "bright, clear" (compare Lithuanian skaidrus "shining, clear;" Old English hador, German heiter "clear, shining, cloudless," Old Norse heið "clear sky").

The Latin word is the source of the usual word for "sky" in most of the Romance languages, such as French ciel, Spanish cielo, Italian cielo, Portuguese céu. Transferred sense of "heavenly, very delightful" in English is from early 15c. Celestial Empire "China" is from 1808, translating native names.

"if stars are infinitely and uniformly distributed through the sky, their number should counterbalance their faintness and the night sky should be as bright as the day;" named for German astronomer H.W.M. Olbers (1758-1840), who propounded it in 1826.