A more thorough explanation:

Definition: Actus proximus (ak-təs prok-si-məs) is a Latin legal term that refers to an immediate act, as opposed to a preparatory act, especially in the commission of a crime.

Example: If someone plans to rob a bank, buying a gun would be a preparatory act. However, actually entering the bank with the gun and demanding money would be considered an actus proximus.

Explanation: The example illustrates the difference between a preparatory act and an immediate act. While buying a gun may be a step towards committing a crime, it is not the actual commission of the crime. The actus proximus, on the other hand, is the immediate act that directly leads to the commission of the crime. In this case, it is entering the bank with a gun and demanding money.