Noun

The property of being lucid, lucidness.

The lucidity of his answers argued against his being insane or confused.

The state of being aware that one is dreaming

The state of being in a lucid dream

Noun

(wikipedia simplicity)

The quality or state of being simple, unmixed, or uncompounded; as, the simplicity of metals or of earths.

The quality or state of being not complex, or of consisting of few parts; as, the simplicity of a machine.

Artlessness of mind; freedom from cunning or duplicity; lack of acuteness and sagacity.

Freedom from artificial ornament, pretentious style, or luxury; plainness; as, simplicity of dress, of style, or of language; simplicity of diet; simplicity of life.

Freedom from subtlety or abstruseness; clearness; as, the simplicity of a doctrine; the simplicity of an explanation or a demonstration.

Freedom from complication; efficiency.

*{{quote-magazine, date=2013-08-03, volume=408, issue=8847, magazine=(The Economist)

, title= Boundary problems , passage=Economics is a messy discipline: too fluid to be a science, too rigorous to be an art. Perhaps it is fitting that economists’ most-used metric, gross domestic product (GDP), is a tangle too. GDP measures the total value of output in an economic territory. Its apparent simplicity explains why it is scrutinised down to tenths of a percentage point every month.}}

Weakness of intellect; silliness; folly.

(rare) An act or instance of foolishness.

*, II.31:

*:speaking of the great simplicity we commit, in leaving yong children under the government and charge of their fathers and parents.