In the past years the Strouhal number has been used to define the nature of cavitation cloud shedding in many studies. In particular, it was adopted as an indicator of a simulation agreement to the experiment. The problem is that there are many interpretations of the parameters that are included in its definition, which leads to a confusion and, as this study shows, to its uselessness. Literature was surveyed and Strouhal numbers with different definitions for several well-defined experiments were calculated. The span of the results exceeded one order of magnitude. The results are discussed and finally, a proposal for a unification of the definition of the Strouhal numberis given.