What does dyspnea mean and what causes it?

Dyspnea is the medical term for difficulty breathing or shortness of breath. It breaks into dys meaning difficult or painful and pnea meaning breathing. Dyspnea can range from mild breathlessness during exertion to severe air hunger at rest. Common causes include asthma, chronic obstructive pulmonary disease, pneumonia, heart failure, anemia, anxiety, and pulmonary embolism. Related terms include tachypnea meaning abnormally fast breathing, bradypnea meaning slow breathing, apnea meaning absence of breathing, and orthopnea meaning difficulty breathing when lying flat.