The term serene has its origin in Latin and is taken from the word serenus. Serenus means serene and clear. When someone or something is described as serene, he or it is said to be calm, peaceful or tranquil. For example: the serene waters of lake. It means unruffled or water without waves or vigorous ripples. Another example: serene demeanour. It means a calm or peaceful manner or conduct.