Merriam-Webster Collegiate Dictionary - enzyme-linked immunosorbent assay

 noun  Date: 1976 an in vitro method for quantifying an antigen or antibody concentration in which the test material is immobilized on a surface and exposed either to a complex of an enzyme linked to an antibody specific for the antigen or an enzyme linked to an antigen specific for the antibody followed by reaction of the enzyme with a substrate to yield a colored product corresponding to the concentration of the test material — called also ELISA