volunteer
noun
a person who voluntarily offers to perform a service or other undertaking.
Used to describe an action that will be fully completed or achieved by a specific point in the future.
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
This year, almost 2,500 people will have volunteered to help host the US Women’s Open.
From The Guardian ● Mar. 28, 2017