Generally, Poetic Diction means the selection of words in a poem or in a prose piece. It denotes the type of language a particular writer chooses for a particular piece of writing. Therefore, poetic diction includes words, phrases, figures of speech, and syntax.
Since different writers have different purposes of writing, their selection of words differs from one another. For this reason, there are several types of poetic diction. It may be formal or informal, literal or figurative, simple or grand, lucid or sonorous, and the like.
However, William Wordsworth used ‘poetic diction’ to mean the ‘gaudy’ language of the Neo-classical writers. To him, the language which was artificial, figurative, elevated, and beyond the reach of common people is ‘poetic diction’.