ensure

synonyms ensure, insure, assure, secure mean to make a thing or person sure. ensure, insure, and assure are interchangeable in many contexts where they indicate the making certain or inevitable of an outcome, but ensure may imply a virtual guarantee <the government has ensured the safety of the refugees>, while insure sometimes stresses the taking of necessary measures beforehand <careful planning should insure the success of the party>, and assure distinctively implies the removal of doubt and suspense from a person's mind <I assure you that no harm will be done>. secure implies action taken to guard against attack or loss <sent reinforcements to secure their position>.