IPA: /ˈtrʌstfəli/
KK: /trʌstfəli/
In a way that shows trust or confidence in someone or something.
She spoke trustfully, believing that her words would be taken seriously.
Trustfully → It is formed from "trust" (from Old Norse "traust", meaning confidence or reliance) and "-fully" (meaning in a manner full of). The word "trustfully" means in a manner full of trust or confidence.
Think of having 'confidence' ('trust') in someone and doing so 'fully' — that's why trustfully means to act with full trust.