The previous “Glossary of Terms for Thoracic Imaging” established by the Fleischner Society profoundly shaped the use of terminology in thoracic radiology over the past decades. Within these guidelines, pulmonary nodules, a term, which is among the most often used by radiologists, were categorized as either “solid”, “ground-glass”, and “part-solid”. These characterizations had wide implications for non-radiologists due to their potential consequences in patient treatment strategies. Despite this, its use was subject to ongoing discussions among physicians, in part, due to its limitation to the mere description of the morphological complexity of a given nodule. The new glossary now proposes an alternative approach, with a distinction between “simple” and “complex” nodules. “Simple” nodules are those with a single structural component, either soft tissue, fat, ground-glass, or calcium. “Complex” nodules are those with two or more components, including all the above, with the addition of air, in all potential combinations. The advantage of this new classification scheme is that it allows to encompass all possible morphologies of “complex” pulmonary nodules, regardless of their degree of complexity. Using mathematical permutation, we first determined the nature and number of all possible 2- and 3-component combinations for “complex” nodules. Second, we conducted a structured search of the teaching file collections of our departments. Third, we selected the most illustrative and educational examples for inclusion in the atlas.