collusive       
adjective uk/kəˈluː.sɪv/ us/kəˈluː.sɪv/
 勾结的,共谋的,串通的
acting together secretly or illegally in order to deceive or cheat someone
  There was evidence of collusive behaviour between the banks. 有证据表明银行之间存在勾结行为。 
 They exchanged collusive smiles. 他们会心一笑。 
 See: collusion
 - More examples
 - There were allegations of collusive behaviour to cover up wrong-doing.
 - These lies are products of collusive ties between news media and the authorities.
 - They could not agree collectively to put up prices as this would be collusive.