Rapidly decreasing response to a drug or physiologically active agent after administration of a few doses. In immunology, it is the rapid immunization against the effect of toxic doses of an extract or serum by previous injection of small doses. (Dorland, 28th ed)
Rapid production of immunity, as is exemplified by the fact, for example, that a second injection of the pressor hormone of the pituitary, a few minutes after the first, produces no further rise of blood pressure (Scbafer.).
A tolerance or immunity acquired within a few minutes by the slow injection of a substance such as the extract of an organ.