1. 先驱；先锋；创始人；倡导者
    Someone who is referred to as a pioneer in a particular area of activity is one of the first people to be involved in it and develop it.

pioneer的翻译

    e.g. ...one of the leading pioneers of British photo journalism...
           英国新闻摄影界的领军人物之一
    e.g. What they lacked in speed those pioneer pilots made up for by flying only a few feet above the ground.
           那些飞行员先驱通过离地仅几英尺的低空飞行，弥补了飞行速度的不足。

2. 开创；倡导
    Someone who pioneers a new activity, invention, or process is one of the first people to do it.

    e.g. ...Professor Alec Jeffreys, who invented and pioneered DNA tests...
           发明和倡导DNA检测的亚历克·杰弗里斯教授
    e.g. The campaigns are part of American-style innovations being pioneered by the new universities.
           这些运动是几所新建大学倡导的美式创新的一部分。

3. 拓荒者；开拓者；开发者
    Pioneers are people who leave their own country or the place where they were living, and go and live in a place that has not been lived in before.

pioneer的翻译

    e.g. ...abandoned settlements of early European pioneers.
           已废弃的早期欧洲拓荒者的定居点