#placidity__repose__quiet__serenity__tranquillity__tranquility  a disposition free from stress or emotion
  supertype:  composure__calm__calmness__equanimity  steadiness of mind under stress; "he accepted their problems with composure and she with equanimity"
  subtype:  ataraxia  peace of mind

No statement uses or specializes placidity; click here to add one.