欺骗(qī piàn) - to deceive, to cheat in Mandarin

欺骗 (qī piàn) is to deceive: a serious, deliberate betrayal of someone's trust. It takes a direct object, 欺骗大家, and it is common in the passive with 被, 我被他欺骗了.

The single character 骗 does the same job in ordinary speech and does it more lightly. 你骗我 is what you say when a friend has wound you up; 你欺骗我 is what you say when the marriage is over. Learners who reach for the two-character word every time end up sounding like a courtroom, so match the weight to the situation.

Two English senses do not transfer. Cheating in an exam is 作弊, and cheating on a partner is 出轨 or 有外遇. 欺骗 also cannot be used for a friendly joke; that is 开玩笑 or 逗. Keep it for cases where somebody was genuinely misled to their cost, which is exactly the register of 欺骗消费者 in a consumer-rights story.