Strategy is a PLAN
To almost anyone you care to ask, strategy is a plan - some sort of consciously intended course of action, a guideline (or set of guidelines) to deal with a situation. A kid has a "strategy" to get over a fence; a firm has one to dominate a market for a particular service or practice area. By this definition, strategies have two essential characteristics: they are developed consciously and purposefully.
Strategy as a PLOY
Strategy can be a ploy, too, which is really just a specific "manoeuvre" intended to outwit an opponent or competitor. The kid may use the fence as a ploy to draw a bully into his yard, where his Doberman Pincher awaits intruders. Likewise, a firm may threaten to establish a new practice area in order to discourage a competitor from trying to do the same. Here the real strategy (as plan, that is, the real intention) is the threat, not the new practice area itself, and as such is a ploy. Threatened litigation often falls into this category.
Strategy is a PATTERN
Strategy (whether as general plans or specific ploys) is pointless if it cannot be realized. In other words, defining strategy as a plan or ploy is not sufficient; we also need a definition that encompasses the resulting behaviour. Thus, strategy is also a pattern - specifically, a pattern in a stream of actions. By this definition, strategy is consistent in behaviour, whether or not intended. The outcome of strategy does not derive from the design, or plan, but from the action that is taken as a result.
Strategy is a POSITION
Strategy is also a position; specifically a means of locating a firm in its environment. In ecological terms: strategy becomes that firm's "niche." In management terms: a "domain" consisting of a particular combination of services, clients and markets. Position is often defined competitively (literally so in the military, where it becomes the site of a battle.)
Strategy is a PERSPECTIVE
While position is outwardly focused, perspective looks inward into the firm; even into the heads of the strategists themselves. Strategy in terms of this definition becomes an ingrained way of perceiving the world. Some firms are aggressive pacesetters; others build protective shells around themselves. Almost every profession has about it unique perspectives, that indelibly flavour the strategies that firms practicing those professions craft for themselves. A law firm's view of their business is fundamentally different to that of an accounting firm, and engineering firm or a graphic design studio, yet all are staffed by professionals.