'Placidness' definitions:

Definition of 'placidness'

(from WordNet)
noun
A feeling of calmness; a quiet and undisturbed feeling [syn: placidity, placidness]

Definition of 'Placidness'

From: GCIDE
  • Placidness \Plac"id*ness\, n. The quality or state of being placid. [1913 Webster]