An essay towards the calculus of functions
Charles Babbage · Abstracts of the Papers Printed in the Philosophical Transactions of the Royal Society of London · 1833
Abstract In the same manner as an exponent expresses one operation on quantity, namely, the multiplication of it by itself a certain number of times, or raising it to the power expressed by that exponent, so the term Function, which has been introduced into modern analysis, is intended to express generally the results of all the various operations that can be performed upon quantity.