Meaning of FUNCTION in English
( n. )
A quantity so connected with another quantity, that if any alteration be made in the latter there will be a consequent alteration in the former. Each quantity is said to be a function of the other. Thus, the circumference of a circle is a function of the diameter. If x be a symbol to which different numerical values can be assigned, such expressions as x2, 3x, Log. x, and Sin. x, are all functions of x.
Webster's Revised Unabridged English Dictionary. Пересмотренный полный словарь английского языка Webster. 2012