a test to determine immunity to diphtheria, made by injecting dilute diphtheria toxin into the skin: if an area of inflammation results, the patient is not immune
See Schick test in American Heritage Dictionary 4
(shĭk)
noun
A test to determine immunity to diphtheria by injection into the skin of dilute diphtheria toxin. Inflammation of the injected area indicates a lack of immunity.