missing exponent
ex·po·nent
ikˈspōnənt,ˈekspōnənt/
noun
1. 1.
a person who believes in and promotes the truth or benefits of an idea or theory.
"an early exponent of the teachings of Thomas Aquinas"
synonyms:
advocate, supporter, proponent, upholder, backer, defender, champion; More
o
2. 2.
MATHEMATICS
a quantity representing the power to which a given number or expression is to be raised, usually expressed as a raised symbol beside the number or expression (e.g., 3 in 23 = 2 × 2 × 2).