When you collude with someone you secretly plot together to do something bad. You might collude with your twin sister to find out where all the birthday presents are hidden.
The word collude entered English in the 16th century from the Latin word colludere, meaning “have a secret agreement,” a combination of col-, meaning “together,” and ludere, meaning “to play.” When you collude with someone, it's like you’re playing together on the same team for the purpose of getting something you want, typically something illegal or harmful. Companies may collude to keep prices high, or politicians may collude to keep damaging information secret.
