The term "corkscrew sign" refers to a specific radiographic appearance associated with two distinct medical conditions: midgut volvulus and diffuse esophageal spasm. In midgut volvulus, it describes the twisted, spiral configuration of the distal duodenum and proximal jejunum. In diffuse esophageal spasm, it represents the corkscrew or rosary bead-like appearance of the esophagus due to abnormal contractions.