Hypoxemia refers to a condition where there is a low level of oxygen in the blood. This condition can be caused by many different factors, including lung diseases, heart diseases, and circulatory problems. Synonyms for hypoxemia include low blood oxygen, oxygen deficiency, inadequate oxygenation, and oxygen deprivation. Other related terms include hypoxia (a lack of oxygen in the body's tissues), anoxia (a complete lack of oxygen), and hypercapnia (an excess of carbon dioxide in the blood). These terms are all important for doctors and healthcare professionals to be familiar with in order to properly diagnose and treat patients with respiratory or cardiovascular issues.