In technical writing, a definition is the process by which one assigns a precise meaning to a term. To define a term, it must be placed into classification and then differentiated from other terms in that same classification. The format for technical definition is straightforward and works like this. Term is classification plus differentiation. For example, if a writer were to define the stall condition that an airplane experiences when it loses lift, he or she could start with the term, stall, and a classification, flight condition, and then differentiate it from all other flight conditions. In this case, by stall's unique characteristics, the definition might be something like this. A stall is a flight condition in which the lift produced becomes less than the weight of the airplane, and the airplane stops flying. That sounds simple enough. But what happens when a term such as stall has multiple definitions in many contexts? In such cases, it may be necessary to add a classifier in front of its definition statement to supply the necessary context. The qualifier is important when the general context for a definition needs to be established upfront. If the context is known, or is obvious, a qualifier isn't necessary. For example, in an aeronautics study on aircraft wing design, the context of stall is obvious. It is clear that stall, in this case, has more to do with the loss of lift than with, say, a defensive maneuver employed by a baseball team to slow down the pace of the game. When a context is needed, the format for the definition is this. Qualifier plus term is classification, which is differentiation. Look at this figure. It provides three definitions of the same term in different contexts. Notice how the term stall has three totally different meanings depending on the context, and how each definition begins with a qualifier that makes the context clear from the start. Car, qualifier, term, classification, in driving, a stall. And a stall is an operating condition in which a sudden and unexpected loss of power occurs. Airplane, in flying, a stall is a flight condition in which the lift produced is less than the weight of the airplane. Cow, in farming, a stall is a simple three-sided compartment that is designed to shelter an animal in a barn or stable. In the first examples, stall refers to a car that has suddenly stopped running. This condition typically occurs in the middle of heavy traffic in bad weather. In the second example, stall refers to what happens when an airplane does not go fast enough to stay in the air. Pilots routinely stall their airplanes right above the runway when landing them, in which case stalling is good. The third example of stall relates to farms, barns, stables and livestock. Often, the most difficult part of writing a technical definition lies in determining the proper classification for the term. The class should be a general category in which the term fits, but it cannot be too general. Let's consider this example, or this sentence. The 33-kilohm, 1-watt carbon resistor is a device that impedes the flow of electric current. The problem with this classification is that the device could mean all kinds of different things, most of which have nothing to do with circuit or circuit components. That is why using this term does not really help specify the meaning of the term. By changing device to circuit component, however, the meaning can be narrowed considerably for the reader, even before the classification is differentiated. So differentiation is very important. The next very important step in defining the term is to differentiate it from all the other members of the class. Differentiation involves narrowing the meaning of the term to just one possibility within the class. Clearly, it would be easier to narrow the class of circuit components to a particular resistor, than it would be to narrow the class of device to a particular resistor. There are all kinds of devices in the world and relatively few circuit components. The class circuit components, however, still contains many possibilities. Capacitors, diodes, switches, potentiometers, inductors, transistors and IC chips, to name a few. In this case, a good approach is to focus on the function of a resistor, which is to impede the flow of electric current, and to use that function to differentiate the class. Then we have the following definition. The 33-kilohm, 1-watt resistor is a circuit component that impedes the flow of electric current. You must always consider the reader's knowledge and skill level when defining terms and concepts. However, at times, you may have no choice but to violate the principle to achieve your goal. Sometimes, a simple term or concept that the audience will understand is just not available. In fact, sometimes the only thing to do is to define the term as best as you can, and then add extensions to your definition to clarify the meaning.
