Definitions
A definition is a statement that gives the meaning of a concept. For simple and relatively concrete concepts such as ‘Table’ we can understand them without definitions by simply seeing them. But most concepts are abstract and complex and to understand them definitions are important tool of knowledge. A definition does the following functions: a. It clarifies the boundaries of a concept. b. It clarifies the relationships among concepts. c. It clarifies the referents of the concepts.
Vagueness and Ambiguity A term is ‘vague’ means it is hazy obscure and imprecise for example the words love, happiness, rich or poor are vague. We can rarely tell whether they apply to a given situation or not. How rich one has to be in order to be called rich? An ‘ambiguous expression’ is one that can be interpreted as having more than one clearly distinct meaning in a given context for example: words such as proper, light, critical, bank can be used ambiguously. If one were to describe an action as proper, does this mean proper in moral sense or proper in the sense of being socially acceptable? The difference between ambiguity and vagueness is that vague terminology allows for a relatively continuous range of interpretations, where as ambiguous terminology allows for multiple discrete interpretations. A vague expression creates a blur of meaning where as ambiguous expression mixes up otherwise clear meanings. Definitions and their purposes
Definition is a group of words that assigns a meaning to some word or group of words. A definition consists of two parts: The definiendum and the definiens. Definiendum is the word or group of words that is supposed to be defined and the definiens is the word or group of words that does the defining.
For example: ‘The “Tiger” means a large, stripped, ferocious feline found in Indian jungles.’
Here the word ‘tiger’ is the definiendum and everything after the word ‘means’ is the definiens.
Definitions are divided into two broad categories: a) Informative (stipulative, lexical, precising theoretical) b) Emotive (persuasive)

I Stipulative definitions
A simulative definition assigns a meaning to a word for the first time. This may involve either coining a new word or giving a new meaning to an old word. Its purpose is to replace a more complex expression with simpler one. A few years ago when scientists were able to crossbreed tiger and lion in a zoo, they needed to give the baby name. They considered many options but they decided to name it ‘liger’.
Stipulative definition is used to set up secret codes in army operations. Because of advancement in science and technology, new creations are coming everyday and stipulative definitions are being used to name them such as download, website, span, bar-code, etc.
It is used for various reasons such as convenience, secrecy, and economy in expression. It is neither true nor false, neither accurate nor inaccurate. i. Lexical definitions
In simple language, it is dictionary definition. It is used to report the meaning that a word already has. As the word has already established meaning, it is either true or false. It helps to eliminate ambiguity. A good lexical definition will distinguish the various shades of a word and erases the possibility of misunderstanding. ii. Precising definitions
It helps to reduce vagueness of a word. A word becomes vague when it is impossible to tell if the word applies or doesn’t apply. Words such as rich, poor, tall are vague and once the vagueness is reduced by a precising definition, the word can be applied to a situation. So instead of saying ‘she is tall’ we can precisely say ‘she is 6 feet tall.’ iii. Theoritical definitions
A theoretical definition assigns a meaning to a word by suggesting a theory that gives a certain characterization to the entities that the term denotes. As theoretical definition functions as a proposal to see or interpret some phenomenon, it is neither true nor false. iv. Persuasive definitions
The purpose of a persuasive definition is to create a favorable or unfavorable attitude toward a word. It is charged with emotion or value-laden meaning. It is the synthesis of lexical, simulative and theoretical definitions backed by the theoretical motive to create certain attitude. For example: ‘Abortion’ means the ruthless murdering of innocent human beings. ‘Abortion’ means safe and established surgical procedure whereby a woman is relieved of an unwanted burden.
This definition’s objective is to influence the attitudes of the reader or listener. Definitional Techniques A. B. Extensional Technique I. Definition by example II. Ostensive Definitions III. Semi-ostensive Definitions C. Intensional Technique I. Synonymous Definitions II. Operational Definitions III. Definition by genus and differentia A. Extensional (Denotative) definitions:
An extensional definition is one that assigns a meaning to a term by indicating the members of the class that the definiendum denotes. There are at least 3 ways of indicating the members of a class: pointing to them (ostensive), giving examples and semi-ostensive. I. Ostensive definition
It is also known as demonstrative definition and it is the most primitive (oldest) form of definition. In it, one needs to know is the meaning of pointing. For example:
‘Chair’ means this and this and this –as one point to several chairs, one after another. They are very limited in use because they require objects for being pointed at. For example, if one wants to define ‘sun’ and it happens to be nighttime, this definition can’t be used.

II. Semi-ostensive or quasiostensive definition
It combines demonstration (pointing) plus some descriptive phrases to the definiens. For example: “The word ‘chair’ means ‘this’ article of furniture.” (Words accompanied by appropriate gesture). It also has limited use like ostensive definition.

III. Definition by Example
It is also known as definition by subclass. It assigns a meaning to a term by naming subclasses of the class denoted by the term. For example:
‘Tree’ means an oak, pine, elm, maple, and the like. ‘Cetacean’ means a whale, a dolphin, or a porpoise. ‘Fictional work’ means a poem, a play, a novel or a short story. B. Intensional (Connotative) definitions:
An intentional definition assigns meaning to a word by indicating the qualities or attributes that the word connotes. There are three types of intentional definitions and they are: I. Synonymous definition
It defines the word in single word. In it, the definiteness is a synonym of the word being defined. For example: ‘Observe’ means see. ‘Physician’ means doctor.
Dictionary heavily relies on this method. It is easy and helpful to learn foreign words but it has serious limitations. They are less accurate and can mislead us. II. Operational definition
Nobel Prize winner physicist P.W Bridgman first used the term. It assigns a meaning to a word by specifying certain experimental procedures that determine whether or not the word applies to a certain thing. For example:
One substance is ‘harder than’ another if and only if one scratches the other when the two are rubbed together.
This definition prescribes an operation to be performed (rub the two substances). It is scientific and it excludes non-extensional nonsense statements. Example: cook-book describes operation by means of which the entity may be extensionally experienced.

III. Definition by genus and differentia
It is also known as ‘definition by division’, ‘analytical definition’ or ‘intensional definition’. It is the most widely used and applicable technique of definition.
‘Genus’ means a relatively larger class and ‘Species’ means a relatively smaller subclass of the genus. For example: let’s see this definition:
Man is a rational animal.
In this definition, the class ‘animal’ whose membership is divided is ‘genus’ and various subclasses such as ‘rational’ are species.
Dictionaries are concerned with words; they often give nothing more than synonyms and rarely provide the full context we need to understand the concept. (Look means watch and watch means look, the meaning is lost.) To define a concept we have to go beyond the dictionary. A definition should include genus and differentia. In this given example, ‘Man is a rational animal’, it has two parts. The term animal names the wider class to which ‘man’ belongs. It classifies ‘man’ as a species of the genus ‘animal’. The term ‘rational’ names/specifies an attribute that distinguishes man from other species of the same genus, which is called differentia. A differentia can rarely be expressed in a single word like rational.
The genus is like our surname/last name that includes the family we belong to; the differentia is like our first name that distinguishes us from other members of our family. The rules for ‘definition by genus and differentia’: a. A definition should include a genus and differentia: Genus shows the similarity and differentia shows the difference of the term.
For example: “Human is featherless biped”, it fails to convey the essential quality of human. It says nothing about the important attribute that distinguishes humans from other animals. It leaves out the genus. The definition should state the essential attributes of the Species. Pick the most essential features you can; look for the attribute that explains the most. For objects in nature, such as biological species or physical substances, look for underlying traits that cause and explain the more superficial attributes. ‘Human’ means animal that has capacity to reason and to speak.

b. A definition shouldn’t be circular:
A definition is circular when the definiendum is defined in terms of itself. For example: ‘Scientist’ means anyone who engages in science. The problem with circularity is that anyone who doesn’t know the meaning of ‘scientist’ would probably not know the meaning of ‘science’. This definition doesn’t go anywhere; it just moves in circle. c. A definition shouldn’t be too broad or too narrow:
A definition is too broad if it includes things that are not referents of the concept. For example: the definition ‘man is a two-legged animal’ is too broad because the defining phrase ‘two-legged animal’ includes birds as well as humans. A definition is too narrow if it fails to include things that are referents of the concept. For example: ‘Man is a religious animal’ is too narrow because no matter how widespread religious belief may be, some people are atheists (who don’t believe in god).
Both are flaws in definition. We can tell whether a definition is too broad or too narrow by looking counter examples, which prove a definition wrong. A counter example is a specific instance that proves a definition wrong. Atheist is a counter example to the definition of a man as a religious animal. Birds are a counter example to the definition of man as a two-legged animal. d. A definition must not be expressed in ambiguous, obscure or metaphorical language:
The purpose of a definition is to clarify the concept but vague, obscure or ambiguous definitions make the definition unclear. Such definition can’t give precise concept. For example:
‘Camel is a ship of the desert.’
Breed may be ‘the staff of life’
A definition should avoid difficult technical jargons, words used in literature.

e. A definition should not use negative words:
A definition shouldn’t use negative unnecessarily where it can be affirmative. A definition should explain what a term does mean rather than what it doesn’t mean. Of the two definitions the first is affirmative; the second is negative:
‘Concord’ means harmony.
Concord means absence of discord.
Some terms are essentially negative in meaning and so require negative definitions.
Bald means lacking hair.
Darkness means the absence of light.
Orphan means a child who doesn’t have parents.
As far as possible, affirmative definitions are much to be preferred over negative ones.