Definition of overvote:
(n) :
(US politics) A case in which a voter has marked a ballot for more choices than allowed by the rules
(v) :
(US politics) To spoil a ballot by marking it for more choices than allowed by the rules
(n) :
(business) A case in which more votes are cast in a voter's name than allowed under the rules
(v) :
(business) To cast more votes than allowed under the rules
(v) :
(obsolete) To outvote or overrule