Adherence to (compliance with) drug treatment is important. However, only about half the people who leave a doctor's office with a prescription take the drug as directed. Among the many reasons people give for not adhering to drug treatment, forgetfulness is the most common.
Definition of periodical. 1  1 : periodic 1. 2  2a : published with a fixed interval between the issues or numbersb : published in, characteristic of, or connected with a periodical.
Periodical literature. Periodical literature (also called a periodical publication or simply a periodical) is a published work that appears in a new edition on a regular schedule.[1] The most familiar example is the magazine, typically published weekly, monthly, or as a quarterly.