IPA: /ˈpaʊəfəli/
KK: /ˈpaʊərfəli/
In a way that has a lot of strength or influence.
She spoke powerfully about the need for change.
Powerfully → It is formed from "power" (from Old French *poeir*, meaning to be able or have strength) and "-fully" (meaning in a manner full of). The word "powerfully" means in a manner full of power or strength.
Think of having a lot of 'strength' ('power') and doing something 'in a manner full of' ('-fully'). This helps you remember that 'powerfully' means doing something with great strength.