“Stakeholder” is simply anyone who will be effected by “x”. whether “x” is a policy change, or something as simple as choosing a new brand of peanut butter for your family.

“Who are the people who will be effected by this?”

In Project Management you’re taught that one of the first things you do when implementing a change or starting a new project, etc… Is to Identify the stakeholders.

I’m sure there’s a more concise definition, but I just woke up.