staple

/ˈsteɪpəl/

(usually plural) a necessary commodity for which demand is constant

中文释义：主食；主要产品；必需品

Rice is a staple food for more than half of the world's population.

大米是全球一半以上人口的主食。

Coffee has become a staple commodity in international trade.

咖啡已成为国际贸易中的主要商品。