Writing Definitions

A formal definition is based upon a concise, logical pattern that permits of a maximum of information in a minimum of space. It consists of three parts.
  • The term (word or phrase) to be defined
  • The class of object or concept to which the term belongs.
  • The differentiating characteristics that distinguish it from all all others of its class

You have readily available to you a number of such definitions, a single sentence in length, which you have been memorizing since grade school days. "Water (term) is a liquid (class) made up of molecules of hydrogen and oxygen in the ratio of 2 to 1 (distinguishing characteristics)." Practice in the writing of such brief formal definitions is good mental discipline as well as excellent training in conciseness and care in the use of words.

In writing a definition:

  • Avoid defining with "is when" and "is where." These adverb phrase introducers do not work well when defining a word. A noun should be defined with a noun, a verb with a verb, an adjective with an adjective.
  • Do not define a word by mere repetition.
  • Define a word in simpler and familiar terms.
  • Keep your class small but adequate. It should be large enough to include all members of the term you are defining but no larger.
  • State the differentiating characteristics precisely.
The Definition Essay

We sometimes offer informal definitions to explain what we mean by a particular term.  Suppose, for example, we say to someone, "Maria is an intelligent girl." We may need to explain what we mean by the term we used "intelligent."

In a definition essay, you provide your personal understanding of a particular concept or term. Your definition essay conveys what your understanding and experience have taught you about the concept or term.

In short, definition is a way of first describing how something is a member of a general class and then how the subject is different from all others of that class.

Consider The Following:

"A microscope is a scientific instrument that is used to help see things that are too small to see with the naked eye.  The word microscope is a combination of two Greek words.  The words are "micros," or "small," and "skopos," or "watcher." So a microscope is a "watcher of the small."

Here the writer will define the term "microscope" by (1) explaining the Greek origin of the word, (2) by describing its parts, and (3) by listing its uses.