Where do you draw the line between enterprise and non-enterprise networking?

A little discussion topic - first post here apologies if this type of discussion isn't really the done thing

I'm not looking for a definition of what an enterprise network would be, I can find one of them online. I'm just wondering at what point- in your opinion- a network becomes large/fast enough etc to be considered an enterprise network

I'd be interested to see what types of responses come up, whether they differ too much or not :)