azure (n.)youdaoicibaDictYouDict
"sky-blue color," early 14c., from Old French azur, asur, a color name, from a false separation of Arabic (al)-lazaward "lapis lazuli," as though the -l- were the French article l'. The Arabic name is from Persian lajward, from Lajward, a place in Turkestan, mentioned by Marco Polo, where the stone was collected.
celestial (adj.)youdaoicibaDictYouDict
late 14c., "pertaining to 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. General sense of "heavenly, very delightful" in English is from early 15c.
cordon (n.)youdaoicibaDictYouDict
mid-15c., "cord or ribbon worn as an ornament," from Middle French cordon "ribbon," diminutive of Old French corde "cord" (see cord). Sense of "a line of people or things guarding something" is 1758. Original sense preserved in cordon bleu (1727) "the highest distinction," literally "blue ribbon," for the sky-blue ribbon worn by the Knights-grand-cross of the Holy Ghost (highest order of chivalry); extended figuratively to other persons of distinction, especially, jocularly, to a first-rate cook. Cordon sanitaire (1857), from French, a guarded line between infected and uninfected districts.