1. in psychological assessment, classifying a patient according to a certain diagnostic category. Patient labeling may be incomplete or misleading, because not all cases conform to the sharply defined characteristics of standard diagnostic categories.

2. medication information provided on a drug container or package insert (also called direction circular or package circular) that specifies indications, side effects, dosages, mechanisms of action, and other information necessary for a physician to prescribe the medication correctly. Drug labeling in the United States is regulated by the U.S. Food and Drug Administration. Also called prescribing information (PI); professional labeling.