exponent
noun [ C ]
uk/ɪkˈspəʊnənt/ usa person who supports an idea or belief:
an exponent of sth Adam Smith was an exponent of free trade.
a person who performs an activity:
an exponent of sth He is one of Japan's master exponents of the art of sushi.
a number or sign which shows how many times another number is to be multiplied by itself:
In 6³ and y², 3 and 2 are the exponents.