Far too often, literature students identify "diction" or "lexis" as a device inappropriately or in a desultory manner, or out of desperation.
What's wrong with saying that the writer "uses diction"?
When you say that "the writer uses diction" to express a certain idea, you are essentially saying that the writer is using words to express that idea.
There is thus no engagement with or interpretation of the writer's use of language.
As such, there is no value in identifying diction if you do not categorise the diction or identify the type of words that the writer uses.
How do I "categorise diction" then?
Like imagery, there are some common/conventional categorisations that we can consider. However, not all common categorisations are applicable; it depends on the context.
So let us look at two ways of categorising diction, A. Common Categories and B. Build Your Own Category.
A. Common Categories
Concrete diction: Concrete diction is the use of words for their literal meanings and often refer to things that appeal to the senses.
Abstract diction: This is when a writer uses words to express something intangible, like an idea or an emotion. Abstract phrases often lack physical detail and specificity because they are things the reader cannot experience through their five senses.
Formal diction: Formal diction is the use of sophisticated language, without slang or colloquialisms. Formal diction sticks to grammatical rules and uses complicated, or at least, proper syntax.
Informal Diction: Informal diction is more conversational and used in non-academic or non-professional settings.
Slang Diction: Similar to informal diction, a subset of informal diction. The language is also very specific to a region and time.
Vernacular : The language or dialect spoken by the ordinary people in a particular country or region.
Pedantic diction: Technical and scholarly language.
Note: This list is not exhaustive.
B. Build your own category
Alternatively, we can turn to our basic knowledge of the English Language. Are we looking at a noun? Or a verb? Or an adjective?
If you realise, the categories in A are often adjectival. Thus, you can consider using appropriate adjectives to describe the writer's style and categorise the diction.
Consider these useful expressions, "diction categorised by", "diction/language characterised by", "diction that can be categorised by its relationship to", "lexis of" and "language of", as in "language characterised by dullness" or "lexis of pain". Let's consider this example from "On Aging" by Maya Angelou: In the poem, the poet depicts the elderly persona's rejection of the "rocking chair" and how her bones are "stiff" and aching". You could thus say that the poet uses diction that can be categorised by its relationship to elderly people/ageing.
Sometimes, the writer's use of language/diction can depict a concept or topic of interest. For example, in William Shakespeare's Macbeth, "Avaunt, and quit my sight!Let/the earth hide thee!”, Shakespeare uses the language of sight, or more specifically, language of visual obscurity to convey Macbeth's avoidance of his guilt of ordering the murder of Banquo.
Further Advice
There are often other more significant language devices such as metaphor, simile, imagery, etc. It is most advisable to focus on them instead, if they are indeed present in the quote that you are examining.
That is not to say that identifying diction is not useful for analysis.
For instance, if you notice that a character uses pedantic diction, or language that is overly formal, such as that of Mr Collins in Pride and Prejudice , you may identify this type of diction and comment on the significance of that diction.
Perhaps, there is a character trait to be derived, or a larger social environment to be discerned through a character's diction.
In the case of Mr Collins, we may comment on his dislikable pretensions/obsequiousness/arrogance, or more importantly, the ironic stupidity/foolishness in his usage of pedantic diction.
