That's what I was thinking: Why don't they just call it a 'big company'? And it's never "an enterprise" or "an enterprise level business"; for some reason it's always "the enterprise", which sounds like a marketing term (or a ship).
Because by definition "The Enterprise" refers to ALL huge companies, not just one. As I said it differentiates a Business sector, or category of businesses. A big business can be one that employs anywhere from 5000 employees to 50,000 employees but still not qualify to be said to be a member of "The Enterprise" class businesses because it doesn't meet those other criteria I listed above. A business that employs from 500 to 5000 employees economically is defined as a small business, contrary from what you might think. It is a definition, a phrase, that specifies a category of businesses. . . It is inclusive of all of them.
I've seen one attempt to define it by the percentage of employees involved in management of the companies. . . i.e. the bureaucracies required to manage an Enterprise level of business. There is a structural change that occurs when a business reaches "The Enterprise" level from mere "Big" or "large" or even "huge" businesses. That attempt failed. . . because some Enterprise level businesses SHRANK their bureaucracies when they grew, while others ballooned their bureaucracies. It was more a matter of management style which grew and which shrank. Nope, that wasn't the answer.