collusion

noun2

1. •
   A private, cooperative agreement or arrangement between groups that otherwise maintain the pretense of competition, contention or non-cooperation.

   • Furthermore, there is good reason for firms to try to collude without express communication, and thus find themselves dealing with less than full mutual understanding. — 2012
2. •
   A private agreement for a fraudulent or illegal purpose; conspiracy.

   • Such tunges unhappy hath made great division In realmes, in cities, by suche fals abusion; Of fals fickil tunges suche cloked collusion — 1515