Prevent, anticipate, forestall mean to deal with beforehand. Prevent implies taking advance measures against something possible or probable. See examples of prevent used in a sentence.
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.
To prevent means to stop something from happening or arising. From middle english preventen ("anticipate"), from latin praeventus, perfect passive participle of praeveniō ("anticipate"), from prae ("before") + veniō ("come"). The verb prevent means "to keep something from happening," like when you use a complicated password to prevent hackers from accessing your account.