Srategy is like pornography...

hard to define, but I know it when I see it. Here are some definitions from economists

• The strategic management field is—positively—the scientific study of the plans that firms build and implement in order to achieve and maintain competitive advantage, and—normatively—the attempt to identify optimal plans for achieving and maintaining competitive advantages
• A field aimed at understanding competitive heterogeneity
• Strategic management is the interdisciplinary field that studies the behavior of companies and other market parties, in terms of their strategic behavior, the choices they make with regard to organizing their production, their interrelationships, and their competitive positioning. All of this is set against a thorough understanding of the broader environment in which companies have to operate

You have to read the article to get the views from scholars in Sociology, Marketing, and Management.