IMO, complete integration (one solution, one vendor) across the board (from OS, to IDE, to Database, to Frameworks, etc) is what makes something "enterprisey". That, and a large and mature ecosystem built around it.
Enterprisey is a matter of perception and shouldn't be a slur.
I actually work at a .NET startup doing non-traditional things with .NET and we have the hardest time hiring new developers because of the "enterprisey" nature of .NET and the type of developer that generates.