That's modules or packages. OO includes inheritance, polymorphism and treating objects as black boxes (little computers in Alan Kay's mental model) with message

That's modules or packages. OO includes inheritance, polymorphism and treating objects as black boxes (little computers in Alan Kay's mental model) with messages they respond to, or APIs for working with that kind of object. It's a lot more than simply being a namespace. It's also that idea that an object has state and behavior, with appropriate semantics for dealing with both (depending on the language). Objects (with classes or prototypes) act as a new kind of data type bundled with functionality for handling that data, which is more than just putting a bunch of functions and variables into a namespace. So you can treat your class/prototype as a built-in complex data type. You're extending the type system in an encapsulated manner. It's not called Namespace Oriented Programming