Definition of

Codomain

The set of all possible output values of a function.

(The set of actual output values is called the range.)

Or in other words the set of values that the output values lie in.

Example: the square of the natural numbers N = {1,2,3,...}:

• the domain (input values) is N
• the codomain (possible output values) is N
• the range (actual output values) is {0,1,2,4,9,16,...}