absorption: absorption n. (in physiology) the uptake of fluids or other substances by tissues of the body. Digested food is absorbed into the blood and lymph from the alimentary canal. Most absorption of food occurs in the small intestine - in the jejunum and ileum - although alcohol is readily absorbed from the stomach. The small intestine is lined with minute finger-like processes (see villus), which greatly increases its surface area and therefore the speed of which absorption can take place. See also assimilation, digestion.