I. sə-ˈrēn adjective
Etymology: Middle English, from Latin serenus clear, cloudless, untroubled
Date: 15th century
1.
a. : clear and free of storms or unpleasant change
serene skies
b. : shining bright and steady
the moon, serene in glory — Alexander Pope
2. : august — used as part of a title
His Serene Highness
3. : marked by or suggestive of utter calm and unruffled repose or quietude
a serene smile
Synonyms: see calm
• se·rene·ly adverb
• se·rene·ness -ˈrēn-nəs noun
II. noun
Date: 1644
1. archaic : a serene condition or expanse (as of sky, sea, or light)
2. archaic : serenity , tranquility