Absorption: Uptake. In the biomedical sciences, absorption has diverse specific meanings.

In the body, absorption is the process whereby a cell, tissue or organ takes up a substance.

In the intestinal tract, absorption is the uptake of food (or other substances) from the digestive tract.

In radiology, absorption refers to the taking up of energy by matter with which the radiation interacts.

In immunology, absorption is the process by which an antibody or antigen is used to remove a corresponding antigen or antibody from a mixture.