Technical definition

Types of technical definitions

There are three main types of technical definitions.

1. Power definitions
2. Secondary definitions
3. Extended definitions

Examples

Aniline, a benzene ring with an amine group, is a versatile chemical used in many organic syntheses.

The genus Helogale (dwarf mongooses) contains two species.

Sentence definitions

These definitions generally appear in three different places: within the text, in margin notes, or in a glossary. Regardless of position in the document, most sentence definitions follow the basic form of term, category, and distinguishing features.

Examples

A major scale is a diatonic scale which has the semitone interval pattern 2-2-1-2-2-2-1.

• term: major scale
• category: diatonic scales
• distinguishing features: semitone interval pattern 2-2-1-2-2-2-1

In mathematics, an abelian group is a group which is commutative.

• term: abelian group
• category: mathematical groups
• distinguishing features: commutative

Extended definitions

When a term needs to be explained in great detail and precision, an extended definition is used. They can range in size from a few sentences to many pages. Shorter ones are usually found in the text, and lengthy definitions are placed in a glossary. Relatively complex concepts in mathematics require extended definitions in which mathematical objects are declared (e.g., let x be a real number...) and then restricted by conditions (often signaled by the phrase such that). These conditions often employ the universal and/or existential quantifiers (for all (\forall), there exists (\exists)).

Note: In mathematical definitions, convention dictates the use of the word if between the term to be defined and the definition; however, definitions should be interpreted as though if and only if were used in place of if.

Examples

Definition of the limit of a single variable function: Let f be a real-valued function of a real variable and x, a, and L be real numbers. We say that the limit of f as x approaches a is L (or, f(x) tends to L as x approaches a) and write \lim_{x\to a} f(x)=L if, for all \epsilon0, there exists \delta0 such that whenever x satisfies 0, the inequality |f(x)-L| holds.

References

References

1. Johnson-Sheehan, R: ''Technical Communication Today'', pages 507-522. Pearson Longman, 2007