Etymology
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cloud nine (n.)
by 1950, sometimes also cloud seven (1956, perhaps by confusion with seventh heaven), American English, of uncertain origin or significance. Some connect the phrase with the 1895 International Cloud-Atlas (Hildebrandsson, Riggenbach and Teisserenc de Bort), long the basic source for cloud shapes, in which, of the ten cloud types, cloud No. 9, cumulonimbus, was the biggest, puffiest, most comfortable-looking. Shipley suggests the sense in this and other expressions might be because, "As the largest one-figure integer, nine is sometimes used for emphasis." The phrase might appear in the 1935 aviation-based play "Ceiling Zero" by Frank Wilbur Wead.
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Cloud Cuckoo Land 

imaginary city built in air, 1830, translating Aristophanes' Nephelokokkygia in "The Birds" (414 B.C.E.). Cloud-land "place above the earth or away from the practical things of life, dreamland, the realm of fancy" is attested from 1840.

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silver lining (n.)

a "bright side" which proverbially accompanies even the darkest trouble; by 1843, apparently from oft-quoted lines from Milton's "Comus," where the silver lining is the light of the moon shining from behind the cloud.

Was I deceived? or did a sable cloud
Turn forth her silver lining on the night?
I did not err, there does a sable cloud,
Turn out her silver lining on the night
And casts a gleam over this tufted grove.

To which Thomas Warton added the commentary: "When all succour ſeems to be lost, Heaven unexpectedly presents the ſilver lining oſ a ſable cloud to the virtuous."

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whole nine yards (n.)
by 1970, of unknown origin; perhaps arbitrary (see cloud nine). Among the guesses that have been made without real evidence: concrete mixer trucks were said to have dispensed in this amount. Or the yard might be the word used in the slang sense of "one hundred dollars." Several similar phrases meaning "everything" arose in the 1940s (whole ball of wax, which is likewise of obscure origin, whole schmear); older examples include whole hog (see hog (n.)) and whole shooting match (1896); whole shebang (1895).
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