1. Extreme incipient inflammatory reaction of the tissues to an injury.
2. The normal response of nerve or muscle to a stimulus.
3. The evocation of a normal or exaggerated reaction in the tissues by the application of a stimulus.
The information shown above for irritation is provided by Stedman's.
* Stedman's, part of Lippincott Williams & Wilkins, provide a comprehensive line of health-science publications for healthcare professionals and medical students.