Synonyms of the word 
PLACIDNESS → CALMNESS - PLACIDITY
placidness
- n. The state or quality of being placid.
calmness
- n. (uncountable) The state of being calm; tranquillity; silence.
- n. (countable) The product of being calm.
placidity
- n. The state of being placid; peacefulness.
If you are interested in words, visit the following sites :
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- 1word.ws/placidness to play with words, suffixs, prefixs, etc.