Collusive

Tom is convinced his teachers are in a collusive plot to force him to learn.

Do not trust to what the French papers say about it. All their encomiums are collusive.

For purposes of evaluating monopsony cases from the standpoint of economic efficiency, it makes sense to adopt a "purpose"-oriented classification system. After all, all monopsony cases can be reduced to either a unilateral or collusive use of buying power in order to promote the interests of the buyer.

Depending on whether they are collusive or competitive, oligopolies can be more like monopolies or more like perfect competition, respectively, as a Khan Academy video explains.