An established or preconceived idea; a fixed notion that is widely accepted and can hinder new thinking.
彼は既成概念にとらわれず、常に新しいアイデアを試す。
He doesn't cling to preconceived notions and is always trying new ideas.
その小説は既成概念を覆す視点で高く評価された。
The novel was highly praised for its perspective that overturns established notions.
既成概念を疑うことは、科学の重要な態度だ。
Questioning established concepts is an important scientific attitude.
会議では既成概念に基づく議論が多かったが、若手が反論した。
At the meeting there were many arguments based on preconceived ideas, but a young member objected.