IPA: /ˈpiːsfəli/
KK: /ˈpisfəlī/
In a way that is calm and free from disturbance or conflict.
The children played peacefully in the garden.
Peacefully → It is formed from "peace" (from Old French *pais*, meaning tranquility or absence of conflict) and "-fully" (meaning full of). The word "peacefully" means full of peace or in a tranquil manner.
Think of the word 'peace' representing tranquility, and remember that 'peacefully' means to act in a manner that is full of peace.