To count more of something than are actually present, or to count one thing disproportionately more than another(verb)
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Use "overcount" in a sentence
"Or was it due to an "overcount" of pigs in the December"
"Mr. Meyer notes that the measures also tend to overstate inflation and overcount the elderly."
"The Gore side gingerly focused on the undercounts, whereas, if memory serves, the overcount ballots would have given them Florida and the White House."