What does this tattoo mean in English? (Character identified: 真)
As an adjective, it means something that is true, real, very.

For example, 

真好!： Really good!

真的吗？ ：Is that true?

真理： The truth

真舒服： Very comfortable!

真实情况： The actual situation.

Here are some helpful link:
http://www.trainchinese.com/v2/wordDetails.php?rAp=0&amp;wordId=3619
https://chinese.yabla.com/chinese-english-pinyin-dictionary.php?define=%E7%9C%9F
http://dictionary.pinpinchinese.com/definitions/s/真-zhen