The act of hardening, or the process of growing hard.

State of being indurated, or of having become hard.

Hardness of character, manner, sensibility, etc.; obduracy; stiffness; lack of pliancy or feeling.

The firmness in the skin test reaction. Induration is produced by immune-cell infiltration in response to tuberculin antigen that was introduced into the skin. It is measured by palpation transversely, and the result is recorded in millimeters (mm). The measurement is compared to guidelines to determine whether the test result is classified as positive or negative.

swelling that can be felt around the site of injection after a Mantoux skin test is done; the reaction size is the diameter of the indurated area (excluding any redness), measured across the forearm

An area of swelling produced by an immune response to an antigen. In tuberculin skin testing or anergy testing, the diameter of the indurated area is measured 48-72 hours after the injection, and the result is recorded in millimeters.