Sed rate, also known as sedimentation rate or erythrocyte sedimentation rate (ESR), refers to the rate at which red blood cells settle in a tube of blood over time. This test is often used as a marker of inflammation or infection in the body. Other words that may be used as synonyms for sed rate include C-reactive protein (CRP) and inflammatory markers. These tests are often used in combination with other diagnostic tools to help healthcare professionals accurately diagnose and manage various health conditions such as rheumatoid arthritis, lupus, infections, and even cancer. It is important to note that a high sed rate does not necessarily mean that a person has a specific disease, and further testing is usually required for confirmation.