exponent
/ɪkˈspəunənt; ɪk`sponənt/ n
1 person or thing that explains and supports a theory, belief, cause, etc （理论、 信仰、 事业等的）倡导者, 拥护者
an exponent of free trade 自由贸易的拥护者
Huxley was an exponent of Darwin's theory of evolution. 赫胥黎是达尔文进化论的鼓吹者.
2 person able to perform skilfully a particular activity （某种活动的）能手
the most famous exponent of mime 最著名的哑剧表演大师
She's a practised exponent of the sport of water-skiing. 她是滑水运动健将.
3 (mathematics 数) figure or symbol that shows how many times a quantity must be multiplied by itself 指数; 幂
In a3, the figure 3 is the exponent. a3中的3是指数.
In xn, the symbol n is the exponent. xn中的n是指数.