defeat
loss in a battle or other contest; opposite of victory
disqualification
removal of a participant's eligibility in a sporting contest for violating the rules
rout
disorderly retreat of troops from a battlefield following a collapse in a given unit's command authority
surrender
cessation of fighting by the losing party
checkmate
winning game position in chess
unseating
a legislator who loses re-election is unseated
loss
defeat credited to a pitcher in baseball