n. 1. (of a point or number) the value of a function corresponding to the given value of the independent variable, or the point into which the given point is mapped. For example, the image of x = 2 under the function y = x² is y = 4. 2. (of a set) the set of values taken by a given function or set-valued function for arguments in that set, written f(S) where S is the given set;
f(S) = {y : y = f(x), x ∈ S}. 3. (of a function) the set of all values of the function, its range as distinct from its codomain.