IPA: /ˈtruːθfəli/
KK: /ˈtruːθfəli/
In a way that is honest and accurate, without hiding the truth.
She answered the questions truthfully during the interview.
Truthfully → It is formed from "truth" (from Old English *triewð*, meaning fidelity or faithfulness) and "-fully" (meaning in a manner full of). The word "truthfully" means in a manner that is full of truth or honesty.
Think of 'truth' as being faithful or honest, and remember that 'truthfully' means to express that honesty in a full manner.