Choice of words for the expression of ideas; the construction, disposition, and application of words in discourse, with regard to clearness, accuracy, variety, etc.; mode of expression; language; as, the diction of Chaucer's poems. His diction blazes up into a sudden explosion of prophetic grandeur. (De Quincey)
style relates both to language and thought; diction, to language only; phraseology, to the mechanical structure of sentences, or the mode in which they are phrased. The style of Burke was enriched with all the higher graces of composition; his diction was varied and copious; his phraseology, at times, was careless and cumbersome. Diction is a general term applicable alike to a single sentence or a connected composition. Errors in grammar, false construction, a confused disposition of words, or an improper application of them, constitute bad diction; but the niceties, the elegancies, the peculiarities, and the beauties of composition, which mark the genius and talent of the writer, are what is comprehended under the name of style.
Origin: L. Dicto a saying, a word, fr. Dicere, dictum, to say; akin to dicare to proclaim, and to E. Teach, token: cf. F. Diction. See Teach, and cf. Benison, Dedicate, index, judge, Preach, Vengeance.