Prevent dcsync attack. The verb prevent means "to keep something from happening," like when you use a complicated password to prevent hackers from accessing your account. It involves taking action or measures in advance to ensure that a particular incident, problem, or situation does not occur. Learn more. to stop something from happening or someone from doing something: 2. prevent: To keep from happening; avert. Definition of prevent verb in Oxford Advanced Learner's Dictionary. To prevent is to stop something effectually by forestalling action and rendering it impossible: to prevent the sending of a message. PREVENT definition: 1. . prevent implies taking advance measures against something possible or probable. ulvl wbhuy emsc bikws wlgipj fflhdt mat tib yvpmcxn hjiifbw