1. Any abnormality indicative of disease, discoverable on examination of the patient; an objective indication of disease, in contrast to a symptom, which is a subjective indication of disease.
2. An abbreviation or symbol.
3. psychology any object or artifact (stimulus) that represents a specific thing or conveys a specific idea to the person who perceives it.
The definition information for sign is provided by Stedman's. You can search our medical dictionary here.
Stedman's, part of Lippincott Williams & Wilkins, provides a comprehensive line of health-science publications for healthcare professionals and medical students.