- A clear fluid secreted by membranes in joint cavities, tendon sheaths, and bursae, and functioning as a lubricant. When a joint disorder is present, the synovial fluid that is removed and examined can contain indicators of disease, such as white blood cells or crystals.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.