Handout 9.1: Summaries, Definitions, and Descriptions
Summaries
A concise and useful summary should include (1) the purpose of the document or procedure
being summarized (2) the most important information (3) the conclusion or results, and (4)
recommendations or implications. Summaries may also have specialized formats, such as
abstracts or executive summaries. For more information on these special formats, refer to
the corresponding Handbook entries.
Definitions
There are three categories of definitions: parenthetical, sentence, and extended.
• A parenthetical definition is a single word or phrase placed within parentheses in a
sentence. Use a parenthetical definition when the definition is useful but not critical to
the reader's understanding of the word or phrase being defined. For example, "Cavies
(guinea pigs) are native to Australia."
• A sentence definition explains the meaning of an unfamiliar word or term by
classifying it; that is, it states the term, groups it with similar items or terms, and then
provides the characteristics that make the word or term unique. For example, "The Miata
is a sports car that is affordable."
If sentence definitions are important to the reader's understanding of the document as a
whole, they should appear near the beginning of the document, usually as part of the
introduction. If definitions are necessary to the understanding of certain sections of a
document, they should appear at the beginning of the appropriate section.
If more than five sentence definitions are necessary, it's a good idea to create a
glossary.
• An extended definition begins with a sentence definition and then expands on it,
enhancing the reader's understanding of the term by adding more information. The
additional information might include the origin of the term, a description of its
components, or a comparison or contrast with something else. Use extended definitions
when the reader's understanding of terms in the document is critical. Abstract terms
frequently require extended definitions.
Descriptions
Accurate descriptions are required in specifications, instructions, catalogs, and lab reports.
Descriptions can be organized chronologically, in order of importance, by function, or in
other ways.
Descriptions should focus on the reader's level of knowledge. If you are writing for more
than one type of reader, write your description for the primary reader. If a description is
required for a secondary reader (for example, the technician who actually builds the new
design), place it in a supplement.