Concepts are cornerstones in science, and their determination is a prerequisite for understanding their substance and meaning. Radiography as a concept is not straightforward nor simple to understand, and there are different interpretations depending on the scientific perspective. To develop truthful knowledge of radiography from the perspective of the discipline, a determination of the subject and substance of radiography is required and thereby is a precursor for theory development. The aim of this study was to investigate the etymological and semantic meaning of radiography from the radiography science perspective. An etymological and semantic analysis has been applied according to Koort and Eriksson's theoretical model. Dictionaries published between 2004 and 2021 were used. The findings show that etymologically, radiography is formed by compounding the words 'radio' and 'graphy', originating historically from Latin and Greek. The semantic analysis revealed that the substance of radiography consisted of four characteristics that are the basic substance of radiography. The characteristics were X-ray and radiation, human beings-opaque objects, process including an act and art and images. This study clarifies the substance and meaning of radiography as a subject from the perspective of radiography science. The subject and substance consisted of the four basic characteristics that all are vital and required to understand the concept of radiography. The characteristics revealed that radiography science is based on scientific knowledge and carrier of properties of meaning that provide a fundamental understanding of radiography science. Investigating the subject, substance and meaning of radiography as a concept can become the base for further theoretical, contextual and practical understanding and support in the development of theory in radiography science.