1.
unauthorized reproduction; unauthorized reposting; reprinting without permission
Copying and republishing someone else's content (text, images, videos, etc.) without obtaining their permission. Extremely common on Japanese websites as a warning against unauthorized sharing.
無断転載禁止。
Unauthorized reproduction prohibited.
この写真の無断転載はご遠慮ください。
Please refrain from reposting this photo without permission.
SNSでの無断転載が問題になり、著作権侵害で訴えられた。
Unauthorized reposting on social media became a problem, and a copyright infringement lawsuit was filed.
Composed of 無断 (without permission) + 転載 (reprinting, reposting). One of the most common copyright-related phrases seen on Japanese websites, blogs, and social media. Almost always appears as 無断転載禁止 (unauthorized reproduction prohibited) or 無断転載はご遠慮ください (please refrain from unauthorized reproduction). Related: 無断使用 (unauthorized use), 無断複製 (unauthorized copying).