Study/Presentation preparation

How to Evaluate a technical definition:

Every technical definition can be evaluated using the criteria listed below.

1. What is the type of definition (parenthetical, sentence, expanded)?

2. Is the type of definition suited to its purpose and user’s needs?
3. Does the definition adequately classify the term?
4. Does the definition clarify, rather than obscure the meaning?
5. Is the definition adequately developed?
6. Is the definition unified and coherent?
7. Are visuals, if used, employed adequately and appropriately?

Defining a Technical Term

Below are three examples of definitions of technical terms.

Read the following three examples of technical definitions, which have been taken from web sites
that are designed to provide information for general readers, and then evaluate each example
using the questions given below. Please use complete sentences.

Example A: Definition of pigment.

A pigment is any substance that absorbs light. The color of the pigment comes from the
wavelengths of light reflected (in other words, those not absorbed). Chlorophyll, the green
pigment common to all photosynthetic cells, absorbs all wavelengths of visible light except green,
which it reflects to be detected by our eyes. Black pigments absorb all of the wavelengths that
strike them. White pigments/lighter colors reflect all or almost all of the energy striking them.
Pigments have their own characteristic absorption spectra, the absorption pattern of a given
pigment.

Absorption and transmission of different wavelengths of light by a hypothetical pigment. Image

from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates
(www.sinauer.com) and WH Freeman (www.whfreeman.com), used with permission.
Example B: Definition of photosynthesis.

Photosynthesis is the fundamental process that maintains life on earth. Living cells convert food
into energy and structural components. Almost all organisms derive this food, directly or
indirectly, from the organic compounds formed within plants during photosynthesis. The stored
energy in these compounds is essential for growth, repair, reproduction, movement, and other
vital functions. Without photosynthesis, not only would replenishment of the fundamental food
supply halt, but the earth would eventually become devoid of oxygen.

Example C: Definition of Sickle Cell Anemia

You will find an example of an extended definition at the following site:

http://www.io.com/~hcexres/textbook/def_ex.html

The following site has some great examples for you to use.
http://www.io.com/~hcexres/textbook/models.html

This information is provided and maintained by David A. McMurrey. For information on use, customization, or copies, e-mail
hcexres@io.com.

What to Define
The words you use will fall into one of the following categories:

1. Familiar words for familiar things (Example: amelioration for improvement, implement
for carry out of fulfil)
2. Familiar words for unfamiliar things. These are everyday simple words that have special
meaning in science and technology. (Example: Puddle. This word is known in the
familiar sense but not everyone knows that in the metallurgical sense, it means a mass of
molten metal. Other examples: apron, chase, cheater, dirty, lake).
3. Unfamiliar words for familiar things (Example: analgesic for painkiller)
4. Unfamiliar words for unfamiliar things. These are specialized terms of professional
groups. Examples: hydrosol, impedance, pyrometer siderite etc.).

You need to define terms familiar to the reader/listener in a different sense from that in which you
are using them; 2) terms unknown to your readers, but which name things that actually are
familiar to them, 3) terms unfamiliar to the readers, and which name scientific and technical
things and processes with which they are also unfamiliar.
Methods of Definition
1. Informal. Informal definition is the substitution of a familiar word or phrase for the
unfamiliar terms used. Instead of a single-word substitution, sometimes a phrase, clause,
or even a sentence may be used in informal definition.
a. However, such definitions are partial, not complete. Informal definitions are
adapted for use in the text of a discussion (they can be fused easily without being
too serious to avoid interruptions). If the definition reaches sentence length, it
lacks the formality and completeness of the sentence definition.
2. With formal definitions, there is a rigid formula, equation-like statement which is
composed of three principal parts: 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 etc. are pointed out so that it is set apart
from the other species. Example
Species = Genus Differentia
Brazing is a welding process wherein the filler metal is a nonferrous metal or
alloy …

Formal definitions involve 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.

Where to put definitions in a report

1. In the text
2. In footnotes
3. In a glossary (at the end of a report), or in a special section in the introduction

It is also convenient to place explanatory notes or words as appositives. Appositives can

sometimes act as a form of a definition.
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Source: Mills, G.H., & Walter, J.A. (1986). Technical Writing. New York: Holt Rinehart and Winston.
pp81 - 91.
Other Types of definitions

Four categories of definitions, each of which has its own appeal:

 Parenthetical definition - When defining a word that the reader will easily understand if shown a
synonym or alternative phrase, show the synonym in parentheses immediately after the word.
Example: The software has received many reviewers' accolades (praises).
 Defining phrase - It is sometimes beneficial to use a term as it is used by the profession you are
writing about, and to follow the term with a few words to explain it. Example: A technical writer
should ask a colleague to proof each draft, to read through it for errors.
 Formal sentence - A formula is given for writing a definition in a sentence. Start with the word or
phrase, state the class (the category the word belongs to), and the distinguishing characteristics
that make it different from other members of its class. Example: An operational definition (phrase)
is the specific meaning of a word or phrase (class) given to it by the group of people who use the
word in their specific context (distinguishing characteristics). Discussed in formal definition above.
 Extended definition - This version of a definition is the longest, offering the freedom to provide
insight into the origin of the term, additional meanings, synonyms and antonyms, and more.
Additional terms are defined here that may be used in definitions:
o denotation - The most basic meaning of a term, usually the first meaning in a dictionary
entry
o connotation - The most familiar meaning of a term to a user
o synonym - Another word or phrase that has the same or almost the same meaning
o antonym - Another word or phrase that has the opposite meaning
o description - As used here, a longer, more detailed description than is provided by a
single formal sentence. This may include a description of each part of a device.
o contrast - A discussion of the term as it compares to a term that has a different meaning
o comparison - A discussion of the term as it relates to a term similar in meaning
o analogy - This method uses similes or metaphors to explain a thing as being like
something else. Example: a network router is a device that works like an airport traffic
controller, keeping network signals moving toward their destinations, and avoiding
collisions between them.
o origin - An explanation of where a term comes from, who first used it, or the
circumstances in which it was first used.
o etymology - A more formal statement about the language roots of a word. Technical
terms may not have actual roots of this sort. The author explains that they are often
acronyms that are better understood when the letters or parts of the word are explained.

Common errors in definitions

Definition fallacies are errors a technical writer might make when writing definitions. Most are easily
understood:

 too technical - The writer has not explained plainly enough.

 too broad - The writer has not focused on what the word means in context.
 too narrow - The writer has not given a definition that is general enough that the reader might
recognize other cases of the thing being defined.
 circular - Typically, the writer has defined a phrase using one of the words in the phrase, or
defined a word using another form of the same word.