They both are titles- Mr. and President. But, Mr. President is a valid address to Mr. Barack Obama. Is it grammatically okay?
I am also confused what if there is a lady president. How do we address her?
They both are titles- Mr. and President. But, Mr. President is a valid address to Mr. Barack Obama. Is it grammatically okay?
I am also confused what if there is a lady president. How do we address her?
1337 is perfectly correct, to expand a bit...
President is both a title and a name substitute depending on how it's used:
President Obama
In this case, President is a title and it applies to Obama.
Mr. President
This is often (if not always) used when addressing the president directly (assuming you aren't a close friend or family). It is the equivalent of using "Your Honor" when addressing a judge. It is a polite way of addressing him without using his name, which might be a little informal.
Other options are:
Mr. Obama
This is often used in news reporting to talk about the president.
POTUS
Acronym for "President of the United States". This is generic and applies to any currently sitting president.
In the case of a female president, the correct term would be:
Madam President
This is just like Nancy Pelosi was "Madam Speaker" when she was Speaker of the House.
It is grammatically okay. In this case, "Mr." is a title and "President" is a name (the name of an office position). As for a lady, she would be referred to as Madam President.
(or something like this)