IPA: /dɪsˈtrʌstfəli/
KK: /dɪsˈtrʌstfəli/
In a way that shows a lack of trust or confidence in someone or something.
She looked at him distrustfully after hearing the rumors.
Distrustfully → It is formed from "dis-" (meaning apart or away) and "trust" (from Old French *troster*, meaning to rely on or have confidence in) and the suffix "-fully" (meaning in a manner full of). The word "distrustfully" means in a manner full of doubt or lack of trust.
Think of being 'apart' ('dis-') from having 'confidence' ('trust') — that's why distrustfully means acting in a way that shows doubt.