serenus

Uncertain, but perhaps from Proto-Indo-European *kseresnos, related to *kseros (“dry”), whence perhaps also serēscō (“to become dry”). See also Ancient Greek ξηρός (xērós), Sanskrit क्षार (kṣārá).^[1][2]

• (Classical Latin) IPA^(key): /seˈreː.nus/, [s̠ɛˈreːnʊs̠]
• (modern Italianate Ecclesiastical) IPA^(key): /seˈre.nus/, [seˈrɛːnus]

serēnus (feminine serēna, neuter serēnum, adverb serēnē); first/second-declension adjective

1. Clear, fair, bright, serene, tranquil.
2. That clears the sky or brings fair weather.
3. (figuratively) Cheerful, glad, joyous, bright; clear, fair, calm, placid, serene
   • 29 BCE – 19 BCE, Virgil, Aeneid 2.285–286:

     “‘[...] Quae causa indigna serēnōs / foedāvit voltūs? [...].’”

     “‘What shameful cause disfigured your serene face?’”
     (Aeneas dreams he is speaking to the dead and disfigured Hector. The Latin plural “serenos voltus,” here translated as English singular, implies a heroic character which projects steadfast calm despite changing circumstances.)

First/second-declension adjective.

• “serenus”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
• “serenus”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
• serenus in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.
• “serenus”, in Harry Thurston Peck, editor (1898), Harper's Dictionary of Classical Antiquities, New York: Harper & Brothers