demography /dɪˈmɑːgrəfi/ noun Learner's definition of DEMOGRAPHY
[noncount]
: the study of changes (such as the number of births, deaths, marriages, and illnesses) that occur over a period of time in human populations
also : a set of such changes人口学；人口统计学 — demographer
/dɪˈmɑːgrəfɚ/ noun, plural demographers [count]