##### Wiktionary

**inverse function**

n. (context mathematics English) A function that does exactly the opposite of another; formally ''g'' is the inverse function of a function ''f'' if and only if: $forall\; x\; .\; f(x)\; =\; y\; implies\; g(y)\; =\; x$. Notation: $f^\{-1\}$.

##### WordNet

**inverse function**

n. the function obtained by expressing the dependent variable of one function as the independent variable of another; f and g are inverse functions if f(x)=y and g(y)=x

##### Wikipedia

**Inverse function**

In mathematics, if a function *f*(*x*) = *y* is injective, exactly one function *g*(*y*) will exist such that *g*(*y*) = *x*, otherwise no such function will exist. The function *g*(*y*) is called the **inverse function** of *f*(*x*) because it "reverses" *f*(*x*); that is to say *g*(*f*(*x*)) = *x*.

#### Usage examples of "inverse function".

I had often noticed that his fondness for me tended to increase as an __inverse function__ of my proximity.