Cohesion is the grammatical and lexical linking within a text or sentence that holds a text together and gives it meaning. It is related to the broader concept of coherence.
There are two main types of cohesion:
A cohesive text is created in many different ways. In Cohesion in English, M.A.K. Halliday and Ruqaiya Hasan identify five general categories of cohesive devices that create coherence in texts: reference, ellipsis, substitution, lexical cohesion and conjunction.
There are two referential devices that can create cohesion:
There is one more referential device, which cannot create cohesion:
A homophoric reference is a generic phrase that obtains a specific meaning through knowledge of its context. For example, the meaning of the phrase "the Queen" may be determined by the country in which it is spoken.
Ellipsis is another cohesive device. It happens when, after a more specific mention, words are omitted when the phrase must be repeated.
A simple conversational example:
The full form of B's reply would be: "I am going to dance".
A simple written example: The younger child was very outgoing, the older much more reserved.
The omitted words from the second clause are "child" and "was".
A word is not omitted, as in ellipsis, but is substituted for another, more general word. For example, "Which ice-cream would you like?" – "I would like the pink one," where "one" is used instead of repeating "ice-cream."
Lexical cohesion refers to the way related words are chosen to link elements of a text. There are two forms: repetition and collocation. Repetition uses the same word, or synonyms, antonyms, etc. For example, "Which dress are you going to wear?" – "I will wear my green frock," uses the synonyms "dress" and "frock" for lexical cohesion. Collocation uses related words that typically go together or tend to repeat the same meaning. An example is the phrase "once upon a time". This is lexical cohesion.