Source: The Collaborative International Dictionary of English v.0.48
epidemiology \ep`i*de`mi*ol"o*gy\, n. [Epidemy + -logy.] (Med.)
That branch of medicine which studies the incidence and
distribution of disease in a population, and uses such
information to find the causes, modes of transmission, and
methods for control of disease.
[1913 Webster +PJC]