Descriptions and Definitions of Strategy (XIX-Sugar, XX-PJ)
ETYMOLOGY[]
"Strategy" is derived from the Greek word stratēgos, which combines two words: stratos (army) and ago (leading). Stratēgos referred to a 'military commander' during the age of Athenian democracy (Source: The Oxford English Dictionary).
FIRST ENGLISH DEFINITION (post-Clausewitz)[]
1825. Oxford English Dictionary, vol 10. "The art of bringing one's forces as rapidly as possible to the decisive point." (Source: Martin van Creveld, Command in War, 1984, pg 279. Van Creveld writes this as if accounting for a definition found in a 1825 Oxford English Dictionary (OED). This is not to be confused with dates of historical quotes found in the current OED used to trace the earliest uses of a word like this one below from 1810].
1810. Oxford English Dictionary (modern 1987, 2ed, pg 852). The OED cites a C. James, Military Dictionary, 3ed, from 1810. "Strategy differes materially from tactic; the later belonging only to the mechanical movement of bodies, set in motion by the former."
DOCTRINAL DEFINITIONS[]
JP 1-02 definitions of STRATEGY strategy — A prudent idea or set of ideas for employing the instruments of national power in a synchronized and integrated fashion to achieve theater, national, and/or multinational objectives. (JP 3-0)
strategic level of war — The level of war at which a nation, often as a member of a group of
nations, determines national or multinational (alliance or coalition) strategic security
objectives and guidance, and develops and uses national resources to achieve these objectives. Activities at this level establish national and multinational military
objectives; sequence initiatives; define limits and assess risks for the use of military and  other instruments of national power; develop global plans or theater war plans to
achieve those objectives; and provide military forces and other capabilities in accordance with strategic plans. See also operational level of war; tactical level of war.
(JP 3-0)   theater strategy — Concepts and courses of action directed toward securing the objectives of national and multinational policies and strategies through the synchronized and integrated employment of military forces and other instruments of national power. See also national military strategy; national security strategy; strategy. (JP 3-0)
FM 3-0, strategy is defined as “the art and science of developing and employing armed forces and other instruments of national power in a synchronized fashion to secure national or multinational objectives.”7
AFDD 2-1 Air Warfare: Strategy is a means to accomplish an end
MCDP 1-2 Campaigning: Military strategy is the art and science of employing the armed forces of a nation to secure the objectives of national policy by the application of force or the threat of force. It involves the establishment of military strategic objectives, the allocation of resources, the imposition of conditions on the use of force, and the development of war plans.7
 
Strategy is both a product and a process. That is, strategy involves both the creation of plans—specific strategies to deal with specific problems—and the process of implementing them in a dynamic, changing environment. Therefore, strategy requires both detailed planning and energetic adaptation to evolving events.
AUTHORS[]
CLASSICS
Clausewitz from On War: “Strategy [is] the use of engagements for the object of the war” (177).
Jomini: Strategy is the art of making war upon the map (The Art of War, 62).
Moltke: Strategy is a system of expedients (Moltke On the Art of War, 47).
Von Moltke the Elder: "the practical adaptation of the means placed at a general’s disposal to the attainment of the object in view." (source?).
B.H. Liddell Hart from Strategy: “the art of distributing and applying military means to fulfill the ends of policy” (Strategy, 321).
Thomas Schelling: Strategy…is not concerned with the efficient application of force , but with the exploitation of potential force. Military Strategy can no longer be thought of as …the science of military victory. It is now equally, if not more, the art of coercion, of imtimidation and deterrence. Military strategy, whether we like it or not, has become the diplomacy of violence.
John Boyd (briefing note, not necessarily a definition): Penetrate adversary’s moral-mental-physical being to dissolve his moral fiber, disorient his mental images, disrupt his operations, and overload his system, as well as subvert, shatter, seize, or otherwise subdue, those moral-mental-physical bastions, connections, or activities that he depends on, in order to destroy internal harmony, produce paralysis, and collapse adversary’s will to resist.
US AUTHORS WHO INTRODUCED 'WAYS' INTO THE "ENDS, WAYS, MEANS" MODEL
Art Lykke gave coherent form to a theory of strategy with his articulation of the three-legged stool model of strategy which illustrated that strategy = ends + ways + means and if these were not in balance the assumption of greater risk. In the Lykke proposition (model) the ends are “objectives,” the ways are the “concepts” for accomplishing the objectives, and the means are the “resources” for supporting the concepts. The stool tilts if the three legs are not kept in balance. If any leg is too short, the risk is too great and the strategy falls over (Toward an Understanding of Military Strategy, 1986, p 3-7).
Henry Eccles describes strategy as “... the comprehensive direction of power to control situations and areas in order to attain objectives” (source poss 1979, Naval War College Review).
FOUR DEFINITIONS THAT EMPHASIZE STRATEGY AS A 'PLAN' OR 'ROADMAP'
ADM J.C. Wylie from Military Strategy: A plan of action designed in order to achieve some end: a purpose together with a system of measures for its accomplishment” (Military Strategy, 14).
Dr Drew and Dr Snow from Making 21st Century Strategy: "A plan of action that organizes efforts to achieve an objective" (Making Twenty-First-Centruy Strategy, 13).
Codevilla and Seabury from War: Ends and Means: “Strategy is a fancy word for a roadmap for getting from here to there, from the situation at hand to the situation one wishes to attain. Strategy is the very opposite of abstract thinking. It is the intellectual connection between the things one wants to achieve, the means at hand, and the circumstances.”
Richard Betts: Strategy is the essential ingredient for making war either politically effective or morally tenable. It is the link between military means and political ends, the scheme for how to make one produce the other. strategy is a distinct plan between policy and operations, an idea for connecting the two rather than either of the two themselves Definition: Plan for using military means to achieve political ends.
COLIN GRAY
Colin Gray from Teaching 21st Strategy: I choose to define (military) strategy as the direction and use that is made of force and the threat of force for the ends of policy.
Colin Gray in Modern Strategy: “Strategy is the bridge that relates military power to political purpose; it is neither military power per se or political purpose. By strategy I mean the use that is made of the threat of force for the ends of policy. …strategy is neither policy nor armed combat; rather it is the bridge between them" (pg 17).
Colin Gray in Fighting Talk: Twenty Maxims on War and Strategy: Regarded narrowly in its military dimension, it is the bridge that connects the worlds of policy and military power. It is strategy that interprets the meaning of that power to serve the purposes of policy.
Colin Gray in War, Peace, and Victory: Strategy is a constant dialectic between means and ends.
DEFINITIONS EMPHASIZING THE DYNAMMIC OF TWO WILLS
Andre Beaufre: "the art of the dialectic of two opposing wills using force to resolve their dispute" (An Introduction to Strategy, 1963, pg. 22).
Beatrice Heuser: "Strategy is a comprehensive way to try to pursue political ends, including the threat or actual use of force, in a dialectic of wills--there have to be at least two sides to a conflict" (The Evolution of Strategy, 2010, pg 27b).
NOTE: In 2005, Everett Dolman discusses the significance of two-wills in strategy (Pure Strategy, 25) and in 2008, Harry Yarger also highlights this fundamental (Strategy and the National Security Professional, 32). Further, since Clausewitz uses the ‘dual’ metaphor (as in ‘spar’), the two-will aspect was likely a truism to a warrior-practitioner like Clausewitz. But if there is any doubt Clausewitz conceived of strategy with a two wills dynamic, the following quote should clarify. “War, however, is not the action of a living force upon a lifeless mass (total nonresistance would be no war at all) but always the collision of two living forces. The ultimate aim of waging war, as formulated here, must be taken as applying to both sides. Once again, there is interaction…Thus I am not in control: he dictates to me as much as I dictate to him" (On War, 77). Finally, as Liddell Hart explains the greatness of the ‘indirect approach’ he describes its significance “to all problems of the influence of mind upon mind” (Strategy, xx, italics added).
OTHER NOTABLE DEFINITIONS
Edward Luttwak in Strategy: The Logic of War and Peace: Realm of strategy, which encompasses the conduct and consequences of human relations in the context of actual or possible armed conflict.
Marcella and Fought, “Teaching Strategy in the 21st Century”1st Quarter 2009 JFQ. “Strategy is the art of applying power to achieve objectives, within the limits imposed by policy.”
Williamson Murray and Mark Grimsley in The Making of Strategy: “Strategy is a process, a constant adaptation to shifting conditions and cumstances in a world where chance, uncertainty, and ambiguity dominate.”
Dr. Kem’s definition from Campaign Planning, Tools of the Trade: Simply put, strategy is the art and science of applying the resources of a nation to the interests and goals of that nation. This requires the integration of the ends (the purposes or objectives of a nation), the ways (courses of action), and the means (the resources of the nation)
H Richard Yarger in “Towards A Theory of Strategy: Art Lykke and the Army War College Strategy Model” : Strategy is the pursuit, protection, or advancement of these interests through the application of the instruments of power. Strategy is fundamentally a choice; it reflects a preference for a future state or condition. Strategy is all about how (way or concept) leadership will use the power (means or resources) available to the state to exercise control over sets of circumstances and geographic locations to achieve objectives (ends) that support state interests. Strategy provides direction for the coercive or persuasive use of this power to achieve specified objectives. This direction is by nature proactive. It seeks to control the environment as opposed to reacting to it. Strategy is not crisis management. Henry Eccles describes strategy as “... the comprehensive direction of power to control situations and areas in order to attain objectives.”
Alan Stephens and Nicola Baker from Making Sense of War: Strategy is best described as the bridge between policy and operations; that is, as a plan for the employment of military forces in pursuit of political objectives.   David Lonsdale in Understanding Modern Warfare: The art of using military force against an intelligent foe(s) towards the attainment of policy objectives.
Dr. Jack Kem Simply put, strategy is the art and science of applying the resources of a nation to the interests and goals of that nation. This requires the integration of the ends (the purposes or objectives of a nation), the ways (courses of action), and the means (the resources of the nation).
Dr. Hal Winton: "Strategy is the craft of creating a favorable future in large-scale activities of broad scope and significant consequence" (current as of Dec 2010).
Dr. Everett Dolman: Strategy is not a thing that can be poked, prodded, and probed. It is an idea, a product of the imagination. It is about the future, and above all it is about change. It is, in a word, alchemy: a method of transmutation from idea into action. Definition: a plan for attaining continuing advantage (Pure Strategy, 6).
Richard Betts: Strategy is the essential ingredient for making war either politically effective or morally tenable. It is the link between military means and political ends, the scheme for how to make one produce the other. strategy is a distinct plan between policy and operations, an idea for connecting the two rather than either of the two themselves Definition: Plan for using military means to achieve political ends.
Dictionary.com : the science or art of combining and employing the means of war in planning and directing large military movements and operations. Strategy is the utilization, during both peace and war, of all of a nation's forces, through large-scale, long-range planning and development, to ensure security or victory.