Definition

Definition is a passage that explains the meaning of a term (a word, phrase or other set of symbols), or a type of thing.

The term to be defined is the definiendum (plural definienda). A term may have many different senses or meanings. For each such specific sense, a definiens (plural definientia) is a cluster of words that defines it.

Types of Definition:

• Lexical definition of a term, also known as the dictionary definition, is the meaning of the term in common usage. As its other name implies, this is the sort of definition one is likely to find in the dictionary.
  

• Extensional definition of a concept or term formulates its meaning by specifying its extension, that is, every object that falls under the definition of the concept or term in question.
• Intensional definition gives the meaning of a term by specifying all the properties required to come to that definition, that is, the necessary and sufficient conditions for belonging to the set being defined.
• Contextual definition helps to understand the meaning of a particular word with the support of related words within the sentence.
• Stipulative definition is a type of definition in which a new or currently-existing term is given a specific meaning for the purposes of argument or discussion in a given context.
• Ostensive definition conveys the meaning of a term by pointing out examples. This type of definition is often used where the term is difficult to define verbally, either because the words will not be understood (as with children and new speakers of a language) or because of the nature of the term (such as colors or sensations). It is usually accompanied with a gesture pointing out the object serving as an example, and for this reason is also often referred to as "definition by pointing". Ostensive definitions rely on an analogical or case-based reasoning by the subject they are intended to.
• Precising definition is a definition that extends the lexical definition of a term for a specific purpose by including additional criteria that narrow down the set of things meeting the definition.
• Operational definition is a demonstration of a process – such as a variable, term, or object – in terms of the specific process or set of validation tests used to determine its presence and quantity.