caeruleus

• caerulus

Dissimilation of *caeluleus, derived from caelum (“sky, heaven”) +‎ -uleus (diminutive suffix). However, in Classical Latin the word is attested as denoting the color of the rainy sky and that of deep water, and was on the whole associated with water.^[1]

• (Classical Latin) IPA^(key): [kae̯ˈrʊ.ɫe.ʊs]
• (modern Italianate Ecclesiastical) IPA^(key): [t͡ʃeˈruː.le.us]

caeruleus (feminine caerulea, neuter caeruleum); first/second-declension adjective

1. Deep water blue: the deep (blue) color associated with water and with the rainy sky^[2]
   1. Dyed or colored blue
      1. (particularly) Colored with woad
   2. Used as an epithet of sea and river deities or things connected with them
   3. (of serpents) Glossy greenish-blue
   4. (of persons) Blue-eyed
   5. Dark-colored, dusky, gloomy
      1. (of clouds and shadows)
      2. (of things in or associated with the underworld)
   6. (as a proper name) A spring and aqueduct at Rome
2. (rare) Of or connected with the sky, celestial

• In spite of its etymology, in Classical Latin this word was typically connected to the deep (blue) color of moving water primarily and to the sky only secondarily, denoting a darkened sky that may rain. From there, it was also connected to darkness.

First/second-declension adjective.

• caerula
• caerulāns
• caeruleātus
• caeruleum

• → English: cerulean
• → French: céruléen
• → Italian: ceruleo
• → Portuguese: cerúleo
• → Romanian: ceruleu
• → Spanish: cerúleo

• “caeruleus” on page 278 of the Oxford Latin Dictionary (2nd ed., 2012)

• “caeruleus”, in Charlton T. Lewis and Charles Short (1879), A Latin Dictionary, Oxford: Clarendon Press
• “caeruleus”, in Charlton T. Lewis (1891), An Elementary Latin Dictionary, New York: Harper & Brothers
• “caeruleus”, in Gaffiot, Félix (1934), Dictionnaire illustré latin-français, Hachette.