serene

–adjective

1.calm, peaceful, or tranquil; unruffled: a serene landscape; serene old age.
2.clear; fair: serene weather.
3.( usually initial capital letter ) most high or august (used as a royal epithet, usually prec. by his, your, etc.): His Serene Highness.
–noun

4.serenity; tranquillity.
5.Archaic . a clear or tranquil expanse of sea or sky.