From Longman Dictionary of Contemporary Englishfoul playˌfoul ˈplay noun [uncountable] 1 SCCif the police think someone’s death was caused by foul play, they think that person was murdered The police said they had no reason to suspect foul play. Detectives have not ruled out foul play.2 DISHONESTan action that is dishonest, unfair, or illegal, especially one that happens during a sports game
Examples from the Corpus
foul play• The autopsy report showed no evidence of foul play.• There have been rumors of foul play in the last election.suspect foul play• The Royal Newfoundland Constabulary said police did not suspect foul play in Noseworthy's death. 