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

I appreciate how dictionary.com defines the word, they use good diction to define the word diction which may sound like a small matter but to me it is no small feat haha.

Diction is also defined as the style of speaking or writing as dependent upon choice of words. 

I wonder how few people comprehend the word diction in comparison to how many people have ever  used a dictionary; I believe that is irony.