1576, "having great power or force," from L. prævalentem (nom. prævalens), prp. of prævalere "to be more able" (see prevail). Meaning "extensively existing, in general use" is from 1658.
Main Entry: prev·a·lence Pronunciation: 'prev(-&)-l&n(t)s Function: noun : the percentage of a population that is affected with aparticular disease at a given time —compare INCIDENCE 2b