The irrational number among the options provided is \(\pi\).
- \(25\) is a rational number because it can be expressed as \(\frac{25}{1}\).
- \(-\sqrt{25}\) (assuming that's what you meant by \(25 - \sqrt{}\)) is also rational, as \(-\sqrt{25} = -5\).
- \(0\) is a rational number since it can be expressed as \(\frac{0}{1}\).
- \(27\) is a rational number as well because it can be expressed as \(\frac{27}{1}\).
Thus, \(\pi\) is the only irrational number.