In medical terms, SOB stands for shortness of breath, also known as dyspnea. It is a common symptom that can be caused by many conditions, including respiratory diseases such as asthma, COPD, pneumonia, and pulmonary embolism, as well as heart conditions like heart attack, heart failure, and cardiac tamponade. Shortness of breath can also be caused by other conditions such as severe anemia or high fever. In general, SOB is a common feeling that may be the result of being out of shape but could also be a sign of serious medical conditions.