What is the formal definition of diction?

Diction can be defined as style of speaking or writing, determined by the choice of words by a speaker or a writer. Diction, or choice of words, often separates good writing from bad writing ... Firstly, the word has to be right and accurate. Secondly, words should be appropriate to the context in which they are used.

My answer is in the explanation

Explanation:

Formal Diction. Contains language that creates an elevated tone. It is free of slang, idioms, colloquialisms, and contractions. It often contains polysyllabic words, sophisticated syntax, and elegant word choice.