prevalence

英 ['prev(ə)l(ə)ns; 'prevəl(ə)ns; 'prevələns] 美['prɛvələns]

• n. 流行；普遍；广泛

1. the quality of prevailing generally; being widespread;

"he was surprised by the prevalence of optimism about the future"

2. (epidemiology) the ratio (for a given time period) of the number of occurrences of a disease or event to the number of units at risk in the population

3. a superiority in numbers or amount;

"there is a preponderance of Blacks in our prisons"