shadowgraph noun 2verb 2forms 3 noun2 •A shadow-picture; a radiograph or X-ray photograph; a sciagram.`There you have its exemplification, a shadowgraph of vapour, penetrated by a single concrete element - my Mind. — 1930 •An optical technique of visualizing patterns of fluid flow by using differences in refractive index verb2 •To outline in a shadow-picture on a screen. •To take a picture by means of X-ray, radium, or similar source of actinic radiation. formsshadowgraphed · shadowgraphing · shadowgraphs