reproduction prohibited; no reproduction
A fixed phrase used as a notice or label, often seen on websites, books, or images, indicating that copying or republishing is not allowed.
Reproduction of the content on this site is prohibited.
The image says 'reproduction prohibited'.
無断転載 means 'unauthorized reproduction', while 転載禁止 is the prohibition notice itself.
Compound of 転載 (reprinting, reproduction) and 禁止 (prohibition).