University Language Skills

Definition

Definitions are explanations that give the reader information about the meaning of terms and expressions used in a text. They are important...

• when you use specialized terms and want or need to communicate with people outside your area of specialization who might never have encountered a term, or might not know the terms as they are used in your field;
  
• when you use a word or phrase in a non-standard way, to mean something in a given context that your reader might not otherwise understand correctly;
  
• when you use a word that is part of the general, non-specialized lexicon, but probably unfamiliar to your reader.

There are two basic types of definitions: informal and formal.

We encounter informal definitions every day, when we read the newspaper or watch a television documentary, for example. There are three basic types of informal definitions: a) synonyms and paraphrases, and b) "operational" definitions, which describe how something works, and c) "stipulative" definitions, which define a term as it is used in a specific context.

Question: How many definitions can you find on this page; how many different types of definitions are represented?

Formal definitions have three parts: the item (the species = concept or thing that needs defining), the class (the genus = group to which the item belongs), and the differentiation (differentia), in which the item is distinguished from all other members of its class.

Example:

Frequently, you will find a formal definition alone is not sufficient. Clarifying your intended meaning often requires amplifying, or expanding on the basic definition. The following are some common methods of amplification. Choose the one(s) that are appropriate to the particular term you are defining. In other words, if you are explaining an acronym or a foreign term, explaining the origin of the term may be helpful. The above example might be amplified as follows:

A glider is a light, engineless aircraft with elongated wings and lift surfaces designed for long periods of flight after being launched from a towing vehicle or catapult. Once in the air, a glider slowly loses altitude; to stay airborne longer the pilot seeks out rising air currents, called "updrafts," and flies in tight circles in them to gain altitude.

Of course, the author might go on to say more about how the glider gets into the air, what qualifications a glider pilot must have in comparison to, say, a small plane pilot or a commercial or military jet pilot, what materials the glider is made of, what cockpit controls are present and how they affect the glider's flight, how gliding compares to sailing and contrasts with motor-driven aircraft and boats - depending on the writer's purpose and his/her intended audience.

Here is a list of methods of amplification you may find useful when writing your extended definition:

• Derivation: Explain the derivation, or origin of a word, phrase, or acronym.
• Explication: In this context, "explicate" means explaining difficult words in the definition itself.
• Exemplification: Give your readers something concrete to understand: an example of the thing or concept you are defining.
• Analogy: Point out similarities between the thing or concept you are defining and something likely to be familiar to your readers.
• Comparison-Contrast: Show both similarities and differences between the concept or thing you are defining and a similar item; this form of amplification takes advantage of something the readers know in order to explain something they do not know.
• Cause and Effect: This method of amplification is particularly useful for explaining elusive concepts and phenomena (e.g. electricity). Essentially, you "define around" the term by showing what causes it and/or what it, in turn, causes: its effects.
• Analysis: Analysis divides the item into its constituent parts. Readers understand the whole by coming to terms with the definition bit by bit.
• Illustration: Sometimes a picture really is worth a thousand words.

Language tips for writing definitions:

Verbs are typically in the simple present tense and may be either passive or active voice. However, when defining a term related to historical events, organizations or things, use verbs in the simple past tense, and either active or passive voice (e.g. "Reconstruction" was the period immediately following the U.S. Civil War.).

Useful verbs:

Relative pronouns: Remember, who is used for persons, which is used for inanimate objects and animals, when is used for times, and where is used for places.

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