undercount

/ˌʌndərˈkaʊnt/
verb
  1. To count fewer than the actual number; to record a number that is too low.
    • The census may undercount people in rural areas.
    • The survey undercounts the number of students who work part-time.
    • If you undercount the inventory, you will run out of supplies.
Antonyms
noun
  1. A count that is lower than the actual number; an instance of undercounting.
    • The undercount in the election results was later corrected.
    • There was a significant undercount of homeless individuals in the report.
    • The undercount of species affected the conservation plan.