The manner of using words; one's choice and manner of speech (includes politeness levels such as honorifics).
目上の人への言葉遣いに気をつけなさい。
Be careful about how you speak to your superiors.
ビジネスでは適切な言葉遣いが重要だ。
Appropriate language is important in business.
子どもに合わせた簡単な言葉遣いで説明した。
I explained it using simple wording suited to the child.