If one person colludes with another, they co-operate with them secretly or illegally. [disapproval]
Several local officials are in jail on charges of colluding with the Mafia. [VERB + with]
My mother colluded in the myth of him as the swanky businessman. [VERB + in]
The two companies were colluding to exploit consumers. [VERB]
[Also pl-n V to-inf]Synonyms: conspire, scheme, plot, intrigue