Clear, or fair, and calm.Calm; placid; unruffled; undisturbed: as, a serene aspect; a serene soul.An epithet or adjunct to the titles of some persons of very high rank; it is not given to any noble or official in England, and is used chiefly (in the phrase Serene Highness) in rendering the German term Durchlaucht (given to members of certain mediatized houses, and to some other princes) and the French epithet sérénissime.Synonyms 1. Bright, peaceful.—1 and 2. Tranquil, Placid, etc. See calm.—2. Sedate.n. Clearness; serenity; a serene expanse or region.n. Serenity; placidity; tranquillity; calmness.To make clear and calm; tranquilize.To clear; clarify.n. The chilly damp of evening; unwholesome air; blight.