1. Having the property of returning to the original shape after being stretched, compressed, bent, or otherwise distorted.
2. A rubber or plastic band used in orthodontics as either a primary or adjunctive source of force to move teeth. The term is generally modified by an adjective to describe the direction of the force or the location of the terminal connecting points.
The definition information for elastic 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.