Medical Definition of Dyspnea Our Symptoms article on Shortness of Breath (Dyspnea) provides a comprehensive look at the possible causes and treatments of Shortness of Breath (Dyspnea). Dyspnea: Difficult or labored breathing; shortness of breath. Dyspnea is a sign of serious disease of the airway, lungs, or heart. The onset of dyspnea should not be ignored; it is reason to seek medical attention. Understanding COPD Slideshow