exponent (n.)

1706, from Latin exponentem (nominative exponens), present participle of exponere "put forth" (see expound). Earliest use is the mathematical one (said to have been introduced in algebra by Descartes) for the symbol placed above and to the right of another to indicate by what power the base number is to be raised. The sense of "one who expounds" is by 1812. As an adjective, "exemplifying, explicating," from 1580s.