The state or quality of being radiodense, i.e. dense to X-rays or other radiation
In radiography, there are portions that appear light whereas other parts are dark. That’s because certain materials make x-rays and radio waves difficult to pass through, thus producing lighter images on radiographic films. In contrast, those that appear black indicate that the materials allow the passage of radiation rather easily. Thus, in X-ray films, the lighter/whiter portions mean they are biological parts/organs that are radiodense whereas those that are darker pertain to the biological parts/organs that are radiolucent.