The prefix "en-" generally means to cause to be, to put into, or to make. In the words "enable" and "endanger," it implies the action of causing something to happen.
- In "enable," it means to make able or to provide the means to do something.
- In "endanger," it means to put someone or something into danger or to make them vulnerable.
So, in both cases, "en-" signifies a transformation or action affecting the root word.