1. The visual representation of an object, such as a body part or celestial body, for the purpose of medical diagnosis or data collection, using any of a variety of usually computerized techniques, such as ultrasonography or spectroscopy.
2. Psychology. The use of mental images to influence bodily processes and to control pain, or to achieve a goal that one has visualized or imagined.

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.