Colloquial style: a style based on spoken language, using expressions close to everyday speech (opposite: literary/classical style).
エッセイは口語体で書かれていて、親しみやすい。
The essay is written in colloquial style and feels friendly.
学術論文には口語体より文語体のほうが適している場合が多い。
Academic papers are often more suitable in literary style than in colloquial style.
彼は講演で意図的に口語体を使って、聴衆にわかりやすく話した。
He intentionally used colloquial style in his lecture to speak clearly to the audience.