- calm, peaceful, or tranquil; unruffled: a serene landscape; serene old age.
- clear; fair: serene weather.
- (usually initial capital letter) most high or august (used as a royal epithet, usually preceded by his, your, etc.): His Serene Highness.
- serenity; tranquillity.
- Archaic. a clear or tranquil expanse of sea or sky.
- peaceful or tranquil; calm
- clear or brighta serene sky
- (often capital) honoured: used as part of certain royal titlesHis Serene Highness
adj.mid-15c., “clear, calm,” from Latin serenus “peaceful, calm, clear” (of weather), figuratively “cheerful, glad, tranquil,” of uncertain origin; perhaps from a suffixed variant of PIE *ksero- “dry,” source of Greek xeros “dry” (see xerasia). In English, applied to persons since 1630s. Related: Serenely.