Diction; Latin: dictionem (nom. dictio), "a saying, expression, word") in its original, primary meaning, refers to the writer's or the speaker's distinctive vocabulary choices and style of expression in a poem or story. A secondary, common meaning of "diction" means the distinctiveness of speech, the art of speaking so that each word is clearly heard and understood to its fullest complexity and extremity, and concerns pronunciation and tone, rather than word choice and style. This secondary sense is more precisely and commonly expressed with the term enunciation, or with its synonym articulation.

Diction has multiple concerns; register—words being either formal or informal in social context—is foremost. Literary diction analysis reveals how a passage establishes tone and characterization, e.g. a preponderance of verbs relating physical movement suggests an active character, while a preponderance of verbs relating states of mind portrays an introspective character. Diction also has an impact upon word choice and syntax.

Diction comprises eight elements: Phoneme, Syllable, Conjunction, Connective, Noun, Verb, Inflection, and Utterance.