As I know, cout is object of an ostream class. Am I right?

I have the following question: I would like to use another 'command' to output data on the screen.
e.g. instead of

cout << "abc";

i would like to use

my_own_cout << "abc";


I have tried to declare it:
ostream my_own_cout;
But it didn't work. Why is that so?

How to make a 'substitute' for cout?

TNX