Definition
In technology, words have precise, specific meanings; therefore there is a need for defining a technical term clearly. The extent to which a term should be defined or the length of a definition depends on the writer's purpose and the knowledge level of the reader.
Before going to the problem of "how to define", it is better to "think about what should be defined first." It is not possible of course, to set up an absolute list of terms and ideas that would require definition, not even for a specific body of readers, but it is possible and desirable to clarify the point of view from which the problem of definition should be attacked.
The relationships of words to the ideas and things for which they stand can become very complex. However, there is a simple and helpful way of classifying words, as they will appear to your reader. The words will fall into one of the following categories:
1. Familiar words for familiar things
2. Familiar words for unfamiliar things
3. Unfamiliar words for familiar things
4. Unfamiliar words for unfamiliar things
1. Familiar words for Familiar things. The only observation that need be made about the first category is that familiar words for familiar things are fine; they should be used whenever possible. To the extent that they can be used, definition is unnecessary. Nothing is ever gained by using, just for the impressiveness, words that may puzzle the reader.
2. Familiar words for unfamiliar things. The words in this second category present a rather special problem to the technical writer. These are the everyday, simple words that have special meanings in science and technology. Most of them may be classed as "shop talk," or language characteristic of a given occupation. Because they are a part (often a very colorful part) of the language of a specialized field, it is easy to forget that they may not be a part of the vocabulary of the reader, at any rate not in the special sense in which they are used. Consider a term like "quench". Everyone knows this word in the familiar sense, but not everyone knows that in the metallurgical sense it means the dipping of heated steel into water, oil, or other bath, to impart necessary hardness.
3. Unfamiliar words for Familiar things. We condemned writers who prefer big and pretentious words for referents with which their readers are familiar. Such a practice should always be condemned if a simple, familiar term exists which means the same thing. But an unfamiliar word for a familiar thing may be used if there does not exist any simple, familiar term for it. Both convenience and accuracy justify it. Suppose an electrical engineer was writing about special tactical electronic equipment making use of direct wave transmission. It is not likely that he would be satisfied to use the phrase "short wave" when dealing specifically with, say, the 300- to 3000- megacycle band. A more precise phrase is "ultrahigh frequency" (UHF). Your solution is simple: you use the convenient term but you define it.
You will have to judge whether your subject matter demands the use of such terms and whether they are familiar to your readers. If they are needed, or if they are justifiably convenient, and you decide that your readers do not know them, you should define them.
4. Unfamiliar words for unfamiliar things. This category embraces most of those words that are commonly thought of as "technical" terms. They are the specialized terms of professional groups; big, formidable looking (to the non-specialist), they are more often than not of Greek or Latin origin. Terms like "dielectric," "hydrosol," "impedance" are typical.
Methods of Definition
In so far as it is possible to use simple, familiar terminology, the problem of definition may be avoided entirely. In other words, the best solution to the problem of definition is to avoid the need for it. When it is necessary, however, there are two methods or techniques that may be employed. The first may be described as informal; the second, as formal. The second takes two forms: the sentence definition and the extended or amplified definition. Each of these techniques has its own special usefulness.
Informal Sentence Definition
Essentially, informal definition is the substitution of a familiar word or phrase for the familiar term used. It is therefore a technique to be employed only when you are reasonably certain that it is the term alone and not the referent which is unfamiliar to the reader.
Instead of a single-word substitution, sometimes a phrase, clause, or even a sentence may be used in informal definition. Such kinds of definition have general facts and they are worthwhile to be noted and these are:
First, they are partial, not complete definitions. But such illustrations are enough in a discussion where thorough understanding of the terms is not necessary and the writer merely wants to identify the term with the reader's experience.
Second, informal definitions are particularly adapted for use in the text of a discussion. Because of their brevity and informality, they can be fitted smoothly into a discussion without appearing to be serious interruptions.
Third, when the informal definition reaches sentence length, it may not be greatly different from the formal sentence definition. It lacks the emphasis, and usually the completeness however which may be required if a term defines an idea or a thing that is of critical importance in a discussion. In short, if one wants to make certain that the reader understands a term and that the term is important enough to focus special attention on it, he will find the formal sentence definition, and perhaps the amplified definition or article of definition, more effective.
Formal Sentence Definition
The informal definition does not require the application of an unchanging, rigid formula; rather, it is an "in other words" technique - the sort of thing we all do frequently in conversation to make ourselves clear. In formal definition, however, it is different. A logically dictated, equation-like statement is always called for, a statement composed of three principal parts for which there are universally accepted names. These are the species, the genus, and the differentia.
The species is the subject of the definition, or the term to be defined.
The genus is the family or class to which the species belongs.
The differentia is that part of the statement in which the particular species' distinguishing traits, qualities, and so forth are pointed out so that it is set apart from the other species comprising the genus.
| Species | = Genus | + Differentia |
| Brazing | is a welding process | wherein the filler metal is a non-ferrous metal or alloy whose melting point is higher than 1000F but lower than that of the metals alloys to be joined. |
The term - the word or phrase to be defined
The class or genus - the specie or family to which the term belongs
The differentia - that part of the definition which states the distinctive characteristics of the term which distinguishes it from other members of the same class.
Defined as a process, then, formal definition involves two steps:
1. Identifying the species as a member of a family or class
2. Differentiating the species from other members of the same class.
The first step in the process of formal definition is that of identifying a thing as a member of a genus, or class. It is important to choose a genus that will limit the meaning of the species and give as much information as possible. In other words, the genus should be made to do its share of the work of defining. It wouldn't help much, for instance, if a micrometer caliper is a "thing" or "device." Generally speaking, the more informative the genus is made, the less one will have to say in the differentia. The more specific one can be in the genus, the less he has to say in the differentia.
Care must be taken in carrying out the second step of the process of formulating a sentence definition. Here the important point is to see that the differentia actually differentiates - singles out the specific differences of the species. A statement which attempts to differentiate a species must be examined critically to see if the definition is applicable solely to the species that is defined. If the statement is true of something else, it may be sure that the differentia is not sufficiently precise. One way to test a statement is to turn it around and see whether the species is the only term described by the genus and differentia.
Example:
"A C-shaped gauge in which the gap between the measuring faces is minutely adjustable by means of a screw whose end forms one face is a ." "Micrometer caliper" fills the blank, and if the definition is correct, it is the only term that accurately fills the blank. An accurate limiting genus coupled with a precisely accurate differentia will always ensure a good definition.
Practice in the writing of such formal definitions is good mental discipline as well as excellent training in conciseness and care in the use of words. However, extreme care must be taken in order to guard against certain faults that can impair their usefulness. Here are some pointers which must be followed when formulating formal definitions:
1. Define a word in simpler and more familiar terms. The purpose of definition is to clarify, not to confuse. A definition more difficult than the term being defined is useless.
ex:
Not this : An emulsion is a fluid consisting of a microscopically heterogeneous mixture of two normally immiscible liquid phases, in which one liquid forms minute droplets suspended in the other liquid.
Better: An emulsion is a fluid consisting of two microscopically different liquids which are insoluble with each other, wherein, one liquid forms very tiny droplets suspended in the other liquid.
2. Practice grammatical parallelism when defining a term. If the term is a noun, a gerund, or an infinitive, the class should be the same. Avoid defining with "is when," "is where," and "is what." Is, being a linking verb, must be followed by the same type of construction that precedes it and an adverb clause cannot serve as a predicate nominative.
ex:
Not this: To oscillate is moving in a regular manner from side to side or back and forth.
Better: To oscillate is to move in a regular manner from side to side or back and forth.
3. Avoid circular definition which means the explanation of a term using the word itself or any of the derivatives. Nothing is achieved when a term is defined by mere repetition.
ex :
Not this : Engineering is the art and sciences taken up by persons to become engineers.
Better: Engineering is the professional art of directing the great sources of power in nature (matter and energy) for the benefit of man.
4. Do not put the term to be defined in too broad or too narrow a class.
ex :
Too broad: A riffle is a weapon . . . (knives, ice picks, swords, etc. are also weapons.)
Too narrow: A rifle is a gun . . . (pistols, revolvers, etc. are also guns)
Better: A riffle is a firearm with spiral grooves inside its barrel to impart rotary motion to its projectile or bullet and thus render its flight more accurate.
The extended definition is developed using any or a combination of the following methods:
1. Details
A term can be clarified by the addition of related or supporting particulars. To define a mechanism, a vivid description of its various parts will enable the reader to "see" it.
2. examples of instances
General statements particularly abstract definitions are made more concrete when illustrations are cited.
3. analogy, contrast or comparison
Analogy cites similarities. The reader is made to understand an unfamiliar object or idea by comparing it with another object or idea more familiar to the reader. Using contrast, the differences of both objects are cited in order to make the idea clear. Comparison combines the two methods of analogy and contrast (pointing out similarities and differences).
4. word derivation
Extended definitions may be revealing and interesting because they explain the origin of the term or the idea. Definitions such as these are seldom logically adequate but they are often extremely useful illustrations for clarification.
Description of a Mechanism
A mechanism is generally defined as any object or system that has a working part or parts. Most often the term suggests tools, instruments, and machines. But other examples of mechanisms could be the human body and systems like the universe or a city, which is composed of parts that work together like parts of a machine. A technical man constantly works with mechanisms and always needs to understand them; what they do, what they look like, what parts they have, and how these parts work together.
There are three fundamental divisions of the description and these are the introduction, the part-by-part description, and the conclusion.
Because the description of a mechanism seldom constitutes an article or report by itself, the introduction required is usually rather simple. The two elements that need most careful attention are:
1. the initial presentation of the mechanism
2. the organization of the description
Description of a Process
A process is a series of actions, and fundamentally the description of a process is the description of action. The action may be either one of two types. One type is that in which attention is focused on the performance of a human being, or possibly a group of human beings. A simple example is filing a workpiece by hand; in a description of this process, emphasis would fall naturally upon the human skills required. The other type involves action in which a human operator either is not directly concerned at all, or inconspicuous. An instance is the functioning of a contactor.
In describing almost any process, regardless of types there are problems that usually arises and these are:
1. adaptation of the description to the reader
2. overall organization
3. use of illustrations
Adapting the description to the reader depends, as always, upon an analysis of the reader's needs. As in the description of a mechanism, if the reader wishes to use the description as a practical guide, it becomes necessary for the writer to give careful attention to every detail. If the reader is interested only in acquiring a general knowledge of the principles involved and has no intention of trying to perform the process or to direct its performance, the writer should avoid many of the details and emphasize the broad outlines of the process.
The fundamental organization of a process description is simple, consisting merely of an introduction followed by a description of each step in the process in the order in which they occur. But this simplicity is usually marred by the necessity of discussing the equipment and the materials used.
There are basically two ways of incorporating the discussion of equipment and materials into the description as a whole. One is to lump it all together in a section near the beginning; the other is to introduce each piece of equipment and each bit of material as it happens to come up in the explanation of the steps in the process. The advantage of confining the description of equipment and materials to a single section near the beginning is that such discussion does not then interrupt the steps in the action itself. This method is usually practical if the equipment and materials are not numerous. If they happen to be so numerous or so complex that the reader might have difficulty in remembering them, the other method of taking them up as they appear in the process is preferable. The second method is by far the more common.
A process description is organized as follows:
Introduction
Equipment and Materials
Step-by-step description of the action
Conclusion (if necessary)
Classification
Classification is the orderly, systematic arrangement of related things in accordance with a governing principle or basis. The classifier notes the structural and functional relationships among things that constitute a class. In recording this relationships, the classifier employs certain conventional terms. Acquaintance with these convenient terms will make the rest easy to follow.
This term has a loose popular meaning and a more precise technical one. Popularly, classification is almost any act of noting relationships. Technically, classification is the act of locating a specimen of all the different kinds of objects that posses a given characteristic or characteristics. Initially, classification must begin with the recognition that different things posses similar characteristics.
