There are many definitions of strategy. Below are a few from eminent scholars and leaders.
Kenichi Ohmae - Mind of the Strategist
What business strategy is all about is, in a word, competitive advantage... The sole purpose of strategic planning is to enable a company to gain, as efficiently as possible, a sustainable edge over its competitors. Corporate strategy thus implies an attempt to alter a company's strength relative to that of its competitors in the most efficient way.
Sun Tzu - The Art of War
Strategy is the great Work of the organization. In Situations of life or death, it is the Tao of survival or extinction. Its study cannot be neglected.
Alfred Chandler - Strategy and Structure
Strategy is the determination of the long run goals and objectives of an enterprise, and the adoption of courses of action and the allocation of resources necessary for carrying out these goals.
Michael Porter - What Is Strategy? HBR, 1996
Strategy is the creation of a unique and valuable position, involving a different set of activities.