Efficacy: Strengthen or efficiency. The ability to achieve the desired effect. A drug passes efficacy trials if it is effective against the illness for which it is prescribed at the dose tested.

Empowerment: Enabling a target population to take more decisional control over their daily lives. The term is often used in association with vulnerable groups, such as women, homosexuals, and sex workers.

Endemic: Condition of disease that is widespread in a given population.

Epidemic: A disease that spreads through a given population at a rate above average.

Epidemiology: The science concerned with the determination of the specific causes or distribution of a disease, or the interrelation of various factors in determining a disease.