Just in the process of finally submitting my game and one of the fields in iTunes connect is keywords.

My game is called "Ball Frenzy" so I wondered if it is OK to put "ball" as one of the keywords or will the word "ball" in the keyword be enough?

I am sure I read that an app will be rejected if you use a keyword that is a duplicate of a word in your game title. The word "ball" is quite a fundamental keyword for my game so I want to be sure to include it if it is necessary.