style of speaking or writing as dependent upon choice of words

good diction.

the accent, inflection, intonation, and speech-sound quality manifested by an individual speaker, usually judged in terms of prevailing standards of acceptability; enunciation.

noun

command of language , delivery , elocution , eloquence , enunciation , expression , fluency , gift of gab * , inflection , intonation , language , line , lingo , locution , oratory , parlance , phrase , phraseology , phrasing , pronunciation , rhetoric , usage , verbalism , verbiage , vocabulary , wordage , wording , articulation , speech , style , words