In mathematics, an integer is any whole number that can be positive, negative, or zero. However, when we talk about whole numbers, we refer specifically to non-negative integers, which include zero and positive integers only.
Therefore, an example of an integer that is not a whole number would be -3. This number is indeed an integer because it is a complete unit without any decimal or fractional part, but it is not a whole number because whole numbers are defined to be zero and all positive integers (0, 1, 2, 3, …).
In summary, while all whole numbers are integers, not all integers are whole numbers. Negative integers, such as -1, -2, -3, etc., serve as examples of integers that do not qualify as whole numbers.