Diction, n.
Etymology: [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.]
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.
Syn. -- Diction, Style, Phraseology. 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." Crabb.
Shades of meaning
An author's diction is strictly his choice and use of words, with no special reference to thought; expression regards the words simply as the vehicle of the thought. Phrase and phraseology apply to words or combinations of words which are somewhat technical; as, in legal phraseology; in military phrase. Diction is general; wording is limited; we speak of the diction of an author or of a work, the wording of a proposition, of a resolution, etc. Verbiage never bears this sense (see circumlocution.) The language of a writer or speaker may be the national speech he employs; as, the English or French language; or the word may denote his use of that language; as, the author's language is well (or ill) chosen. Style includes diction, expression, rhetorical figures such as metaphor and simile, the effect of an author's prevailing tone of thought, of his personal traits--in short, all that makes up the clothing of thought in words; thus, we speak of a figurative style, a frigid or an argumentative style, etc., or of the style of Macaulay, Prescott, or others. An author's vocabulary is the range of words which he brings into his use. Compare language.