>COLLUSION
noun
secret or illegal cooperation or conspiracy, especially in order to cheat or deceive others.
"the armed forces were working in collusion with drug traffickers"
synonyms: conspiracy, connivance, complicity, intrigue, plotting, secret understanding, collaboration, scheming
"there had been collusion between the security forces and paramilitary groups"
LAW
illegal cooperation or conspiracy, especially between ostensible opponents in a lawsuit.