1. 最重要的;最好的
    The foremost thing or person in a group is the most important or best.

    e.g. He was one of the world's foremost scholars of ancient Indian culture...
           他是世界上最杰出的古印第安文化研究者之一。
    e.g. The military government is waging a war of words against its supposed enemies. Foremost among these are the foreign media.
           军政府针对假想的敌人展开了一场唇枪舌剑的战斗。这其中首当其冲的就是外国媒体。

2. 首先;首要的是
    You use first and foremost to emphasize the most important quality of something or someone.

    e.g. It is first and foremost a trade agreement...
           这首先是一个贸易协议。
    e.g. I see myself, first and foremost, as a working artist.
           我首先还是把自己看作一名艺术工作者。