In electoral systems, a wasted vote is any vote which is not for an elected candidate or, more broadly, a vote that does not help to elect a candidate. The narrower meaning includes only those votes which are for a losing candidate or party. The broader definition of wasted votes includes votes for winning candidates in excess of the minimum needed to win.
Wasted votes are the basis of the efficiency gap measure of gerrymandering, where voters are grouped into electoral districts in such a way as to increase the wasted votes of one political faction and decrease the wasted votes of the other.
Even more broadly, a vote is said to be qualitatively wasted in the judgment of the voter when their vote has been needlessly added to a candidate who is less valued than a more valued and available candidate.