Thanks for your question on Healthcare Magic. I can understand your concern. Shortness of breath is defined in many ways. There is no particular definition for this. But as doctors, we call it shortness of breath when patient is having rapid breathing, (respiratory rate more than 24 per minute), with use of accessory respiratory muscles with hypoxia (low oxygen saturation). Patient usually describe shortness of breath as breathing difficulty on climbing stairs or fast walking. Some patients describe this as labored breathing. So there is no specific definition for shortness of breath. Hope I have solved your query. I will be happy to help you further. Wish you good health. Thanks.