“In mathematics, a function1 is a relation between a set of inputs and a set of permissible outputs with the property that each input is related to exactly one output. An example is the function that relates each real number x to its square x2. The output of a function f corresponding to an input x is denoted by f(x) (read "f of x").” (wikipedia)
It seems like function has two meanings: (1) a relation between two variables, (2) the output of the function. Is this right? Or does f in ‘f of x’ only mean the output of a function, not just function?