Relating to not permitting the passage or transmission of x-rays: Roentgenopaque or radiopaque X-rays are impenetrable to certain materials and so an image is produced on a radiosensitive surface; such as, photographic film, by radiation other than with visible light.

There are roentgenopaque materials that are not penetrable by roentgen rays at the commonly used diagnostic energy procedures. Such roentgenopaque areas appear light or white on exposed films.