My definition of a project is any endeavor that has:
A goal is simply “the outcome the project is trying to achieve.” It could be a successful staff retreat, a website redesign, or a kid’s birthday party—there is something you are trying to have happen in the real world that will enable you to mark it “complete.”
A deadline adds a time limit to achieving your goal. You don’t want your efforts lingering on forever, never quite knowing whether you succeeded or failed. Having some kind of end point in mind (whether strict and externally imposed or informal and self-imposed) allows you to ask yourself, “How much can I get done with the time remaining?”