Is Java a Platform independent?

Is Java a platform independent?

During our work in the graduation project a question came to our minds.. is Java a platform independent?

mmm.. according to our readings .. the answer should be..YES!

but according to the last year graduation work, the answer will be turned to NO!
I will not say the reasons in this post, but at least when I got the "Right" definition of "platform indepenedent".
I think the word "platform independent" has another meaning in Java..
So what do u think ? what does platform independent mean?