IPA: /ˈkɑːm.nəs/
KK: /kɑm.nəs/
The state of being peaceful and free from strong emotions or disturbances.
She found calmness in the quiet of the early morning.
Calmness is formed from "calm" (from Old French *calme*, meaning quiet or peaceful) and "-ness" (meaning the state or quality of). The word "calmness" refers to the state of being calm or peaceful.
Think of the word 'calm' which means peaceful, and remember that 'calmness' describes the state of being peaceful.