enumerate (something, especially a sector of a population in a census) at a lower figure than the actual figure: they have been accused of undercounting the homeless Baltimore’s population was undercounted by about 36,000 people
noun
Pronunciation: /ˈʌndəkʌʊnt/
a count or figure that is inaccurately low: an undercount would thwart this progress
the amount by which such a count or figure falls short of the actual figure: other states had significantly larger undercounts