Final answer:
A very large project impacting over a million people and costing over a billion dollars is known as a Mega Project, characterized by its extensive scope and societal impact.
Step-by-step explanation:
A project that is typically described as a very large project, often costing over 1 billion dollars, impacting over one million people, and lasting several years is known as a Mega Project. These projects are typically characterized by their substantial scale and complexity, requiring considerable resources and multi-disciplinary collaboration. Historical examples of mega projects include monumental architecture like the ancient Egyptian pyramids, Medieval European cathedrals, or large infrastructure undertakings like the dams built in the western United States. Each underscores the involvement of extensive materials, labor, and the organization of large numbers of people operating within a social structure, often driven by governments, corporations, or other large organizations.