WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
noun.
a feeling of calmness; a quiet and undisturbed feeling
noun.
a disposition free from stress or emotion
Word Usage
"The other is elitism, a charge that clearly grates on him and unnerves his wife, who has a great deal that would be attractive in a first lady (intelligence, accomplishment, beauty) but lacks placidity, which is, actually, necessary."