IPA: /ˌvɒlənˈtɛrəli/
KK: /vɑːlənˈtɛrəli/
In a way that is done by choice or free will, without being forced or required.
She decided to help the community voluntarily, without expecting anything in return.
Voluntarily → It is formed from "voluntas" (meaning will or wish) and the suffix "-ly" (meaning in a manner). The word "voluntarily" means in a manner that is done by one's own will or choice.
Think of 'will' ('voluntas') to remember that 'voluntarily' means doing something by your own choice.