自愿免费、无偿地为社会进步或文明发展贡献自己力量的人volunteer

• 美方表示，被打死的人中多是来叙利亚的志愿者。

  The United States said that most of the people killed were volunteers in Syria.

• 在志愿服务的过程中，志愿者收获到了快乐。

  In the course of volunteering, volunteers reap joy.