runoff runoff /ˈrʌˌnɔf/

noun

1. () The occurrence of surplus liquid (as water) exceeding the limit or capacity  ( overflow , overspill , runoff )
   the occurrence of surplus liquid (as water) exceeding the limit or capacity
   
2. A final election to resolve an earlier election that did not produce a winner  ( runoff )
   a final election to resolve an earlier election that did not produce a winner
    The results were so close that they had to schedule a runoff election.
   The results were so close that they had to schedule a runoff election.